{"id":"CVE-2026-66038","state":"PUBLISHED","title":"FFmpeg LCL/ZLIB Video Decoder Information Disclosure via lcldec.c","description":"FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer bytes than the expected frame size. The zlib_decomp() function in lcldec.c treats short decompression as non-fatal and continues to the RGB24 conversion path, which copies a full frame's worth of rows from the allocation buffer using original frame dimensions, causing uninitialized heap contents including pointer-derived allocator bytes to be copied into the attacker-observable AVFrame output and potentially defeating ASLR in long-lived media processing services.","publishedAt":"2026-07-24T19:39:27.448Z","updatedAt":"2026-07-28T01:06:28.780Z","severity":{"score":7.1,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","source":"VulnCheck"},"assigner":"VulnCheck","products":["FFmpeg FFmpeg"],"affected":[{"vendor":"FFmpeg","product":"FFmpeg","defaultStatus":"affected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"8.1.2","versionType":"semver"},{"version":"86708357d126af84c16f80d9c57335d1e8c845c5","status":"unaffected","versionType":"git"}],"repo":"https://code.ffmpeg.org/FFmpeg/FFmpeg"}],"references":["https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626","https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e862c8c","https://www.vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-disclosure-via-lcldec-c"],"weaknesses":["CWE-908"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/66xxx/CVE-2026-66038.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-66038","state":"PUBLISHED","datePublished":"2026-07-24T19:39:27.448Z","dateUpdated":"2026-07-28T01:06:28.780Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-07-23T20:45:17.816Z"},"containers":{"cna":{"title":"FFmpeg LCL/ZLIB Video Decoder Information Disclosure via lcldec.c","descriptions":[{"lang":"en","value":"FFmpeg through 8.1.2, fixed in commit 8670835, contains an information disclosure vulnerability in the LCL/ZLIB video decoder that allows attackers to expose uninitialized heap memory by supplying a valid zlib stream that inflates to fewer bytes than the expected frame size. The zlib_decomp() function in lcldec.c treats short decompression as non-fatal and continues to the RGB24 conversion path, which copies a full frame's worth of rows from the allocation buffer using original frame dimensions, causing uninitialized heap contents including pointer-derived allocator bytes to be copied into the attacker-observable AVFrame output and potentially defeating ASLR in long-lived media processing services."}],"affected":[{"vendor":"FFmpeg","product":"FFmpeg","defaultStatus":"affected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"8.1.2","versionType":"semver"},{"version":"86708357d126af84c16f80d9c57335d1e8c845c5","status":"unaffected","versionType":"git"}],"repo":"https://code.ffmpeg.org/FFmpeg/FFmpeg"}],"references":[{"url":"https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626","name":"Pull Request","tags":["issue-tracking"]},{"url":"https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e862c8c","name":"Patch Commit","tags":["patch"]},{"url":"https://www.vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-disclosure-via-lcldec-c","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"HIGH","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"HIGH","baseScore":7.1,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"NONE","version":"3.1","baseSeverity":"MEDIUM","baseScore":6.5,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-908","lang":"en","description":"Use of Uninitialized Resource","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-07-28T01:06:28.780Z"},"tags":["x_open-source"],"datePublic":"2026-07-04T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:ffmpeg:ffmpeg:*:*:*:*:*:*:*:*","versionEndIncluding":"8.1.2"}]}]}],"credits":[{"lang":"en","value":"Adrian Junge (vurlo)","type":"finder"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"vulncheck"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-24T20:14:10.590088Z","id":"CVE-2026-66038","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-24T20:14:17.998Z"}}]}}}