171 lines
7.0 KiB
JSON
171 lines
7.0 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-2026-7840",
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"assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
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"state": "PUBLISHED",
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"assignerShortName": "securin",
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"dateReserved": "2026-05-05T07:30:59.460Z",
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"datePublished": "2026-07-01T03:33:28.957Z",
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"dateUpdated": "2026-07-09T04:36:16.157Z"
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},
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"containers": {
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"cna": {
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"title": "UltraVNC repeater HTTP server global buffer overflow via long URI (pre-auth RCE)",
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"descriptions": [
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{
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"lang": "en",
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"value": "UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP administration server. The functions wi_senderr() and wi_replyhdr() in repeater/webgui/webutils.c write the caller-supplied HTTP request URI into a fixed 1000-byte global buffer (hdrbuf) via unchecked sprintf calls. The HTTP receive buffer accepts URIs up to approximately 150 KB (WI_RXBUFSIZE = 153600), so an unauthenticated attacker who can reach the repeater HTTP port (default TCP 80) can overflow hdrbuf by at least 500 bytes with a single HTTP request containing a URI of 1500 bytes or longer, corrupting adjacent .bss-segment globals. The overflow occurs before any authentication check, making it reachable without credentials. A remote, unauthenticated attacker can achieve arbitrary code execution on the host running the repeater."
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}
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],
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"affected": [
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{
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"vendor": "uvnc",
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"product": "UltraVNC",
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"versions": [
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{
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"version": "0",
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"lessThanOrEqual": "1.8.2.2",
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"status": "affected",
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"versionType": "custom"
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}
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],
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"defaultStatus": "unaffected",
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"modules": [
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"repeater"
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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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"type": "CWE",
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"cweId": "CWE-787",
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"lang": "en",
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"description": "Out-of-bounds Write"
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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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"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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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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"attackVector": "NETWORK",
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"attackComplexity": "LOW",
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"privilegesRequired": "NONE",
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"userInteraction": "NONE",
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"scope": "UNCHANGED",
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"confidentialityImpact": "HIGH",
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"integrityImpact": "HIGH",
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"availabilityImpact": "HIGH",
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"baseScore": 9.8,
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"baseSeverity": "CRITICAL"
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},
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"cvssV4_0": {
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"version": "4.0",
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"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
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"baseScore": 9.3,
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"baseSeverity": "CRITICAL"
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}
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}
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],
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"references": [
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{
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"url": "https://uvnc.com/",
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"name": "UltraVNC project page",
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"tags": [
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"vendor-advisory"
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]
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},
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{
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"url": "https://github.com/ultravnc/UltraVNC",
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"name": "UltraVNC source repository",
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"tags": [
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"product"
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]
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},
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{
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"url": "https://www.securin.io/zero-days/cve-2026-7840-pre-auth-global-buffer-overflow-repeater-http-admin-ultravnc"
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}
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],
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"timeline": [
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{
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"time": "2026-06-02T00:00:00.000Z",
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"lang": "en",
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"value": "Vulnerability discovered during security audit"
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},
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{
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"time": "2026-06-17T00:00:00.000Z",
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"lang": "en",
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"value": "Reported to vendor (coordinated disclosure)"
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},
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{
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"time": "2026-09-15T00:00:00.000Z",
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"lang": "en",
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"value": "Planned public disclosure (90-day window)"
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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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"value": "Arjun Basnet, Securin (arjun.basnet@securin.io)",
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"type": "finder"
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}
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],
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"source": {
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"discovery": "EXTERNAL",
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"advisory": "Securin Security Advisory — FINDING-005"
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},
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"providerMetadata": {
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"orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
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"shortName": "securin",
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"dateUpdated": "2026-07-09T04:36:16.157Z"
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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": "2026-07-01T12:33:40.320112Z",
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"id": "CVE-2026-7840",
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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": "yes"
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},
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{
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"Technical Impact": "total"
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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": "2026-07-01T12:33:48.634Z"
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}
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}
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]
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}
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} |