287 lines
15 KiB
JSON
287 lines
15 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-2026-55735",
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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": "2026-06-17T10:44:34.365Z",
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"datePublished": "2026-08-01T18:46:05.234Z",
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"dateUpdated": "2026-08-03T19:30:07.608Z"
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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:ueberauth:guardian:*:*:*:*:*:*:*:*"
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],
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"defaultStatus": "unaffected",
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"modules": [
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"'Elixir.Guardian'"
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],
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"packageName": "guardian",
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"packageURL": "pkg:hex/guardian",
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"product": "guardian",
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"programFiles": [
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"lib/guardian.ex"
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],
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"programRoutines": [
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{
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"name": "'Elixir.Guardian':revoke/3"
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}
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],
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"repo": "https://github.com/ueberauth/guardian",
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"vendor": "ueberauth",
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"versions": [
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{
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"lessThan": "2.4.1",
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"status": "affected",
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"version": "1.0.0",
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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:ueberauth:guardian:*:*:*:*:*:*:*:*"
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],
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"defaultStatus": "unaffected",
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"modules": [
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"'Elixir.Guardian'"
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],
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"packageName": "ueberauth/guardian",
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"packageURL": "pkg:github/ueberauth/guardian",
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"product": "guardian",
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"programFiles": [
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"lib/guardian.ex"
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],
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"programRoutines": [
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{
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"name": "'Elixir.Guardian':revoke/3"
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}
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],
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"repo": "https://github.com/ueberauth/guardian",
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"vendor": "ueberauth",
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"versions": [
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{
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"lessThan": "2bd7a8c29770d423d855c0a4965caa6c3e486901",
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"status": "affected",
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"version": "d65227145f72b290106c06cecbe42728fbf05fe2",
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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 route a caller-supplied token into <tt>Guardian.revoke/3</tt> (for example a logout or session-revocation endpoint) and use a token module whose <tt>revoke</tt> / <tt>on_revoke</tt> callback mutates state keyed by the token claims (a whitelist that deletes by <tt>jti</tt> or a blacklist that inserts by <tt>jti</tt>, such as a GuardianDb-style store). With the default no-op <tt>on_revoke</tt> callback, no session state is changed and the issue is not exploitable.</p>"
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}
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],
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"value": "The application must route a caller-supplied token into Guardian.revoke/3 (for example a logout or session-revocation endpoint) and use a token module whose revoke / on_revoke callback mutates state keyed by the token claims (a whitelist that deletes by jti or a blacklist that inserts by jti, such as a GuardianDb-style store). With the default no-op on_revoke callback, no session state is changed and the issue is not exploitable."
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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:ueberauth:guardian:*:*:*:*:*:*:*:*",
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"versionEndExcluding": "2.4.1",
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"versionStartIncluding": "1.0.0",
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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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}
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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": "Yordis Prieto"
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},
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{
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"lang": "en",
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"type": "analyst",
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"value": "Jonatan Männchen / EEF"
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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 Verification of Cryptographic Signature in ueberauth guardian allows an unauthenticated attacker to revoke a victim's session with a forged token.</p><p><tt>Guardian.revoke/3</tt> in <tt>lib/guardian.ex</tt> decodes the supplied token with <tt>peek/1</tt>, which performs no signature verification (it only base64-decodes the JWT header and payload). The resulting unverified claims are forwarded directly to the configured token module's <tt>revoke</tt> callback and the implementation's <tt>on_revoke</tt> callback, a state-mutating sink. The sibling operations <tt>refresh/2</tt> and <tt>exchange/4</tt> both call <tt>decode_and_verify</tt> first, so the signature is checked before anything acts on the claims; <tt>revoke/3</tt> is the only state-mutating path that acts on claims without verifying the signature.</p><p>An attacker who knows or guesses a victim's identifying claim values (<tt>jti</tt>, <tt>sub</tt>) can forge a JWT carrying those claims, sign it with an arbitrary key, and submit it to any endpoint that funnels a caller-supplied token into <tt>Guardian.revoke/3</tt> (the standard logout / session-revocation pattern). When the token module mutates state keyed by the claims (whitelist deletion or blacklist insertion, for example a GuardianDb-style store), the victim's legitimate session is evicted. This is an unauthenticated session-revocation denial of service; the attacker never needs the signing secret.</p><p>This issue affects guardian: from 1.0.0 before 2.4.1.</p>"
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}
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],
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"value": "Improper Verification of Cryptographic Signature in ueberauth guardian allows an unauthenticated attacker to revoke a victim's session with a forged token.\n\nGuardian.revoke/3 in lib/guardian.ex decodes the supplied token with peek/1, which performs no signature verification (it only base64-decodes the JWT header and payload). The resulting unverified claims are forwarded directly to the configured token module's revoke callback and the implementation's on_revoke callback, a state-mutating sink. The sibling operations refresh/2 and exchange/4 both call decode_and_verify first, so the signature is checked before anything acts on the claims; revoke/3 is the only state-mutating path that acts on claims without verifying the signature.\n\nAn attacker who knows or guesses a victim's identifying claim values (jti, sub) can forge a JWT carrying those claims, sign it with an arbitrary key, and submit it to any endpoint that funnels a caller-supplied token into Guardian.revoke/3 (the standard logout / session-revocation pattern). When the token module mutates state keyed by the claims (whitelist deletion or blacklist insertion, for example a GuardianDb-style store), the victim's legitimate session is evicted. This is an unauthenticated session-revocation denial of service; the attacker never needs the signing secret.\n\nThis issue affects guardian: from 1.0.0 before 2.4.1."
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}
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],
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"impacts": [
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{
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"capecId": "CAPEC-475",
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"descriptions": [
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{
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"lang": "en",
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"value": "CAPEC-475 Signature Spoofing by Improper Validation"
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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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"attackComplexity": "LOW",
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"attackRequirements": "PRESENT",
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"attackVector": "NETWORK",
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"baseScore": 8.2,
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"baseSeverity": "HIGH",
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"privilegesRequired": "NONE",
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"subAvailabilityImpact": "NONE",
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"subConfidentialityImpact": "NONE",
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"subIntegrityImpact": "NONE",
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"userInteraction": "NONE",
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"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
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"version": "4.0",
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"vulnAvailabilityImpact": "HIGH",
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"vulnConfidentialityImpact": "NONE",
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"vulnIntegrityImpact": "NONE"
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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-347",
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"description": "CWE-347 Improper Verification of Cryptographic Signature",
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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": "2026-08-01T18:46:05.234Z"
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},
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"references": [
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{
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"tags": [
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"vendor-advisory",
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"related"
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],
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"url": "https://github.com/ueberauth/guardian/security/advisories/GHSA-7975-hp3r-5qhv"
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},
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{
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"tags": [
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"related"
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],
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"url": "https://cna.erlef.org/cves/CVE-2026-55735.html"
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},
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{
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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-2026-55735"
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},
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{
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"tags": [
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"patch"
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],
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"url": "https://github.com/ueberauth/guardian/commit/2bd7a8c29770d423d855c0a4965caa6c3e486901"
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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": "Guardian.revoke/3 acts on unverified token claims, allowing forged-token session revocation",
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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>Verify the token before revoking it: call <tt>decode_and_verify</tt> (or a verify-without-expiry variant, so already-expired tokens remain revocable) on the caller-supplied token and pass only tokens whose signature validates into <tt>Guardian.revoke/3</tt>. Reject tokens with an invalid signature at the application boundary.</p>"
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}
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],
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"value": "Verify the token before revoking it: call decode_and_verify (or a verify-without-expiry variant, so already-expired tokens remain revocable) on the caller-supplied token and pass only tokens whose signature validates into Guardian.revoke/3. Reject tokens with an invalid signature at the application boundary."
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}
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],
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"x_generator": {
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"engine": "cvelib 1.8.0"
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}
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},
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"adp": [
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{
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"references": [
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{
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"url": "https://github.com/ueberauth/guardian/security/advisories/GHSA-7975-hp3r-5qhv",
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"tags": [
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"exploit"
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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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"other": {
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"type": "ssvc",
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"content": {
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"timestamp": "2026-08-03T19:29:43.841542Z",
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"id": "CVE-2026-55735",
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"options": [
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{
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"Exploitation": "poc"
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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": "2026-08-03T19:30:07.608Z"
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}
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}
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]
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}
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} |