314 lines
17 KiB
JSON
314 lines
17 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-43971",
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"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
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"state": "PUBLISHED",
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"assignerShortName": "EEF",
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"dateReserved": "2026-05-04T18:23:25.574Z",
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"datePublished": "2026-08-18T09:01:53.199Z",
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"dateUpdated": "2026-09-16T20:24:09.279Z"
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},
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"containers": {
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"cna": {
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"affected": [
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{
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"collectionURL": "https://repo.hex.pm",
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"cpes": [
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"cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"
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],
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"defaultStatus": "unaffected",
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"modules": [
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"cow_link"
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],
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"packageName": "cowlib",
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"packageURL": "pkg:hex/cowlib",
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"product": "cowlib",
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"programFiles": [
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"src/cow_link.erl"
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],
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"programRoutines": [
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{
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"name": "cow_link:link/1"
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},
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{
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"name": "cow_link:do_link/1"
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},
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{
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"name": "cow_link:escape/2"
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}
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],
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"repo": "https://github.com/ninenines/cowlib",
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"vendor": "ninenines",
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"versions": [
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{
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"lessThan": "2.20.0",
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"status": "affected",
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"version": "2.9.0",
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"versionType": "semver"
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}
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]
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},
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{
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"collectionURL": "https://github.com",
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"cpes": [
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"cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"
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],
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"defaultStatus": "unaffected",
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"modules": [
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"cow_link"
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],
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"packageName": "ninenines/cowlib",
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"packageURL": "pkg:github/ninenines/cowlib",
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"product": "cowlib",
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"programFiles": [
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"src/cow_link.erl"
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],
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"programRoutines": [
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{
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"name": "cow_link:link/1"
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},
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{
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"name": "cow_link:do_link/1"
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},
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{
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"name": "cow_link:escape/2"
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}
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],
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"repo": "https://github.com/ninenines/cowlib",
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"vendor": "ninenines",
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"versions": [
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{
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"lessThan": "89da27ee4c241f5d649ba7d9b7f2188918af6cea",
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"status": "affected",
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"version": "485d58dfa91b91d98135dc95e5615f421715dae5",
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"versionType": "git"
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}
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]
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}
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],
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"configurations": [
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{
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"lang": "en",
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"supportingMedia": [
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{
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"base64": false,
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"type": "text/html",
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"value": "<p>The application must pass values that originate from, or can be influenced by, untrusted input into <code>cow_link:link/1</code> — specifically the target URI, rel value, or attribute keys. Applications that construct Link entries exclusively from trusted, application-controlled values are not affected.</p>"
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},
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{
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"base64": false,
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"type": "text/markdown",
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"value": "The application must pass values that originate from, or can be influenced by, untrusted input into `cow_link:link/1` — specifically the target URI, rel value, or attribute keys. Applications that construct Link entries exclusively from trusted, application-controlled values are not affected."
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}
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],
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"value": "The application must pass values that originate from, or can be influenced by, untrusted input into cow_link:link/1 — specifically the target URI, rel value, or attribute keys. Applications that construct Link entries exclusively from trusted, application-controlled values are not affected."
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"cpeMatch": [
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{
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"criteria": "cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*",
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"versionEndExcluding": "2.20.0",
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"versionStartIncluding": "2.9.0",
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"vulnerable": true
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}
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],
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"negate": false,
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"operator": "OR"
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}
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],
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"operator": "AND"
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}
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],
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"credits": [
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{
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"lang": "en",
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"type": "finder",
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"value": "Peter Ullrich"
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},
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{
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"lang": "en",
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"type": "remediation developer",
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"value": "Jonatan Männchen / EEF"
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},
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{
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"lang": "en",
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"type": "remediation reviewer",
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"value": "Loïc Hoguin"
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}
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],
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"descriptions": [
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{
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"lang": "en",
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"supportingMedia": [
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{
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"base64": false,
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"type": "text/html",
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"value": "<p>Improper Encoding or Escaping of Output vulnerability in ninenines cowlib allows Link header directive smuggling via unescaped special characters in <code>cow_link:link/1</code>.</p>\n<p><code>cow_link:do_link/1</code> in cowlib interpolates the target URI, rel value, and attribute keys directly into the serialized <code>Link:</code> header value without escaping or token-grammar validation. A <code>></code> byte in target prematurely closes the URI slot, allowing an attacker to append additional link entries with attacker-chosen rel directives. A <code>\"</code> or <code>\\</code> in rel escapes the quoted string and opens new parameters. Any byte — including whitespace, <code>=</code>, and <code>\"</code> — in an attribute key is emitted verbatim. Because browsers act on <code>Link:</code> directives such as <code>rel=\"preconnect\"</code>, <code>rel=\"preload\"</code>, and <code>rel=\"prerender\"</code>, an attacker who can influence these fields in an application that round-trips parsed Link headers through <code>cow_link:link/1</code> can force victim browsers to make out-of-band connections to attacker-controlled origins.</p>\n<p>This issue affects cowlib: from 2.9.0 before 2.20.0.</p>"
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},
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{
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"base64": false,
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"type": "text/markdown",
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"value": "Improper Encoding or Escaping of Output vulnerability in ninenines cowlib allows Link header directive smuggling via unescaped special characters in `cow_link:link/1`.\n\n`cow_link:do_link/1` in cowlib interpolates the target URI, rel value, and attribute keys directly into the serialized `Link:` header value without escaping or token-grammar validation. A `>` byte in target prematurely closes the URI slot, allowing an attacker to append additional link entries with attacker-chosen rel directives. A `\"` or `\\` in rel escapes the quoted string and opens new parameters. Any byte — including whitespace, `=`, and `\"` — in an attribute key is emitted verbatim. Because browsers act on `Link:` directives such as `rel=\"preconnect\"`, `rel=\"preload\"`, and `rel=\"prerender\"`, an attacker who can influence these fields in an application that round-trips parsed Link headers through `cow_link:link/1` can force victim browsers to make out-of-band connections to attacker-controlled origins.\n\nThis issue affects cowlib: from 2.9.0 before 2.20.0."
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}
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],
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"value": "Improper Encoding or Escaping of Output vulnerability in ninenines cowlib allows Link header directive smuggling via unescaped special characters in cow_link:link/1.\n\ncow_link:do_link/1 in cowlib interpolates the target URI, rel value, and attribute keys directly into the serialized Link: header value without escaping or token-grammar validation. A > byte in target prematurely closes the URI slot, allowing an attacker to append additional link entries with attacker-chosen rel directives. A \" or \\ in rel escapes the quoted string and opens new parameters. Any byte — including whitespace, =, and \" — in an attribute key is emitted verbatim. Because browsers act on Link: directives such as rel=\"preconnect\", rel=\"preload\", and rel=\"prerender\", an attacker who can influence these fields in an application that round-trips parsed Link headers through cow_link:link/1 can force victim browsers to make out-of-band connections to attacker-controlled origins.\n\nThis issue affects cowlib: from 2.9.0 before 2.20.0."
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}
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],
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"impacts": [
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{
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"capecId": "CAPEC-137",
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"descriptions": [
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{
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"lang": "en",
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"value": "CAPEC-137 Parameter Injection"
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}
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]
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}
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],
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"metrics": [
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{
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"cvssV4_0": {
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"Automatable": "NOT_DEFINED",
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"Recovery": "NOT_DEFINED",
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"Safety": "NOT_DEFINED",
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"attackComplexity": "LOW",
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"attackRequirements": "PRESENT",
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"attackVector": "NETWORK",
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"baseScore": 6.3,
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"baseSeverity": "MEDIUM",
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"privilegesRequired": "NONE",
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"providerUrgency": "NOT_DEFINED",
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"subAvailabilityImpact": "NONE",
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"subConfidentialityImpact": "NONE",
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"subIntegrityImpact": "LOW",
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"userInteraction": "NONE",
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"valueDensity": "NOT_DEFINED",
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"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N",
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"version": "4.0",
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"vulnAvailabilityImpact": "NONE",
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"vulnConfidentialityImpact": "NONE",
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"vulnIntegrityImpact": "LOW",
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"vulnerabilityResponseEffort": "NOT_DEFINED"
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},
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"format": "CVSS",
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"scenarios": [
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{
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"lang": "en",
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"value": "GENERAL"
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}
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]
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}
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],
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"problemTypes": [
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{
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"descriptions": [
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{
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"cweId": "CWE-116",
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"description": "CWE-116 Improper Encoding or Escaping of Output",
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"lang": "en",
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"type": "CWE"
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}
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]
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}
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],
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"providerMetadata": {
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"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
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"shortName": "EEF",
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"dateUpdated": "2026-09-16T20:24:09.279Z"
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},
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"references": [
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{
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"name": "EEF CNA record for CVE-2026-43971",
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"tags": [
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"related",
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"third-party-advisory"
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],
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"url": "https://cna.erlef.org/cves/CVE-2026-43971.html"
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},
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{
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"name": "OSV record EEF-CVE-2026-43971",
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"tags": [
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"related"
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],
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"url": "https://osv.dev/vulnerability/EEF-CVE-2026-43971"
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},
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{
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"name": "Introducing commit 485d58d in ninenines/cowlib",
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"tags": [
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"related"
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],
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"url": "https://github.com/ninenines/cowlib/commit/485d58dfa91b91d98135dc95e5615f421715dae5"
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},
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{
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"name": "Fix commit 89da27e in ninenines/cowlib",
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"tags": [
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"patch"
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],
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"url": "https://github.com/ninenines/cowlib/commit/89da27ee4c241f5d649ba7d9b7f2188918af6cea"
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}
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],
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"source": {
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"discovery": "EXTERNAL"
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},
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"title": "Link Header Directive Smuggling via Unescaped target/rel/Attribute Keys in cow_link:link/1",
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"workarounds": [
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{
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"lang": "en",
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"supportingMedia": [
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{
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"base64": false,
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"type": "text/html",
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"value": "<p>Sanitize values before passing them to <code>cow_link:link/1</code>: reject or strip any target value containing <code>></code>, any rel value containing <code>\"</code> or <code>\\</code>, and any attribute key containing characters outside the HTTP token grammar. Alternatively, ensure all Link entry fields are derived exclusively from trusted, application-controlled values rather than untrusted input.</p>"
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},
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{
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"base64": false,
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"type": "text/markdown",
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"value": "Sanitize values before passing them to `cow_link:link/1`: reject or strip any target value containing `>`, any rel value containing `\"` or `\\`, and any attribute key containing characters outside the HTTP token grammar. Alternatively, ensure all Link entry fields are derived exclusively from trusted, application-controlled values rather than untrusted input."
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}
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],
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"value": "Sanitize values before passing them to cow_link:link/1: reject or strip any target value containing >, any rel value containing \" or \\, and any attribute key containing characters outside the HTTP token grammar. Alternatively, ensure all Link entry fields are derived exclusively from trusted, application-controlled values rather than untrusted input."
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}
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]
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},
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"adp": [
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{
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"timestamp": "2026-08-18T14:11:55.645955Z",
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"id": "CVE-2026-43971",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"role": "CISA Coordinator",
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"version": "2.0.3"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-08-18T14:12:35.495Z"
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}
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}
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]
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}
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} |