{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-50538", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-04T20:37:18.653Z", "datePublished": "2026-08-21T21:03:58.147Z", "dateUpdated": "2026-08-21T21:03:58.147Z"}, "containers": {"cna": {"title": "libvncclient Tight decoder has an attacker-controlled heap out-of-bounds write", "problemTypes": [{"descriptions": [{"cweId": "CWE-122", "lang": "en", "description": "CWE-122: Heap-based Buffer Overflow", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-787", "lang": "en", "description": "CWE-787: Out-of-bounds Write", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1"}}], "references": [{"name": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-v9pm-47h4-jcq8", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-v9pm-47h4-jcq8"}, {"name": "https://github.com/LibVNC/libvncserver/commit/540332be3e0acc566fa64da6f1b4680c72c724dd", "tags": ["x_refsource_MISC"], "url": "https://github.com/LibVNC/libvncserver/commit/540332be3e0acc566fa64da6f1b4680c72c724dd"}], "affected": [{"vendor": "LibVNC", "product": "libvncserver", "versions": [{"version": ">= 0.9.12, <= 0.9.15", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-21T21:03:58.147Z"}, "descriptions": [{"lang": "en", "value": "LibVNCClient is a library for easy implementation of a VNC client. In versions 0.9.12 through 0.9.15, a malicious (or man-in-the-middle) VNC server can force a connecting `libvncclient` to write attacker-controlled data past the end of its framebuffer. This is an out-of-bounds heap write with attacker-controlled length, contents, and offset. It needs no authentication (the attacker\nis the server), works in a default build with default settings, and fires from a single `FramebufferUpdate` the moment the victim connects. It crashes any client unconditionally (denial of service); we also demonstrated it overwriting an application callback pointer and redirecting execution to attacker-chosen code (code execution) under the default configuration. Commit 540332be3e0acc566fa64da6f1b4680c72c724dd patches the issue."}], "source": {"advisory": "GHSA-v9pm-47h4-jcq8", "discovery": "UNKNOWN"}}}}

{}

{"affected": [{"affectedData": [{"product": "libvncserver", "vendor": "LibVNC", "versions": [{"status": "affected", "version": ">= 0.9.12, <= 0.9.15"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "LibVNCClient is a library for easy implementation of a VNC client. In versions 0.9.12 through 0.9.15, a malicious (or man-in-the-middle) VNC server can force a connecting `libvncclient` to write attacker-controlled data past the end of its framebuffer. This is an out-of-bounds heap write with attacker-controlled length, contents, and offset. It needs no authentication (the attacker\nis the server), works in a default build with default settings, and fires from a single `FramebufferUpdate` the moment the victim connects. It crashes any client unconditionally (denial of service); we also demonstrated it overwriting an application callback pointer and redirecting execution to attacker-chosen code (code execution) under the default configuration. Commit 540332be3e0acc566fa64da6f1b4680c72c724dd patches the issue."}], "id": "CVE-2026-50538", "lastModified": "2026-08-21T21:16:59.807", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.9, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-21T21:16:59.807", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/LibVNC/libvncserver/commit/540332be3e0acc566fa64da6f1b4680c72c724dd"}, {"source": "security-advisories@github.com", "url": "https://github.com/LibVNC/libvncserver/security/advisories/GHSA-v9pm-47h4-jcq8"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-122"}, {"lang": "en", "value": "CWE-787"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{}