{"id":"CVE-2026-125197","state":"PUBLISHED","title":"FFmpeg through 9.0.2 Heap Out-of-Bounds Read via LCL/ZLIB Multithread Decoding","description":"FFmpeg through 9.0.2 contains an integer underflow in decode_frame() in libavcodec/lcldec.c that allows attackers to trigger a heap out-of-bounds read via short ZLIB packets with FLAG_MULTITHREAD. Attackers can supply a crafted AVI or MKV file with an LCL video stream whose packet is shorter than 8 bytes, bypassing length clamping to crash the decoding application.","publishedAt":"2026-11-09T19:11:17.977Z","updatedAt":"2026-11-09T19:11:17.977Z","severity":{"score":6.9,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N","source":"VulnCheck"},"assigner":"VulnCheck","products":["FFmpeg FFmpeg"],"affected":[{"vendor":"FFmpeg","product":"FFmpeg","packageURL":"pkg:github/ffmpeg/ffmpeg","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"9.0.2","versionType":"semver"}],"repo":"https://code.ffmpeg.org/FFmpeg/FFmpeg"}],"references":["https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25020","https://github.com/FFmpeg/FFmpeg/commit/12e5d4ec98b7add7bcac9d8131d9a6dfb2549966","https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/lcldec.c#L287","https://github.com/FFmpeg/FFmpeg","https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-out-of-bounds-read-via-lcl-zlib-multithread-decoding"],"weaknesses":["CWE-191"],"ingestedAt":"2026-11-09T19:14:06.399Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/125xxx/CVE-2026-125197.json","commit":"61d6df80db1b12b1399aa01bc455626e606d2471","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-125197","state":"PUBLISHED","datePublished":"2026-11-09T19:11:17.977Z","dateUpdated":"2026-11-09T19:11:17.977Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-11-09T18:15:10.953Z"},"containers":{"cna":{"title":"FFmpeg through 9.0.2 Heap Out-of-Bounds Read via LCL/ZLIB Multithread Decoding","descriptions":[{"lang":"en","value":"FFmpeg through 9.0.2 contains an integer underflow in decode_frame() in libavcodec/lcldec.c that allows attackers to trigger a heap out-of-bounds read via short ZLIB packets with FLAG_MULTITHREAD. Attackers can supply a crafted AVI or MKV file with an LCL video stream whose packet is shorter than 8 bytes, bypassing length clamping to crash the decoding application."}],"affected":[{"vendor":"FFmpeg","product":"FFmpeg","packageURL":"pkg:github/ffmpeg/ffmpeg","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"9.0.2","versionType":"semver"}],"repo":"https://code.ffmpeg.org/FFmpeg/FFmpeg"}],"references":[{"url":"https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25020","tags":["issue-tracking"]},{"url":"https://github.com/FFmpeg/FFmpeg/commit/12e5d4ec98b7add7bcac9d8131d9a6dfb2549966","tags":["patch"],"name":"Patch Commit"},{"url":"https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/lcldec.c#L287","tags":["technical-description"]},{"url":"https://github.com/FFmpeg/FFmpeg","tags":["product"]},{"url":"https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-out-of-bounds-read-via-lcl-zlib-multithread-decoding","name":"VulnCheck Advisory: FFmpeg through 9.0.2 Heap Out-of-Bounds Read via LCL/ZLIB Multithread Decoding","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N","attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":6.9,"baseSeverity":"MEDIUM"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"NONE","availabilityImpact":"HIGH","baseScore":6.1,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-191","lang":"en","description":"Integer Underflow (Wrap or Wraparound)","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-11-09T19:11:17.977Z"},"datePublic":"2026-10-12T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:ffmpeg:ffmpeg:*:*:*:*:*:*:*:*","versionEndIncluding":"9.0.2"}]}]}],"credits":[{"lang":"en","value":"Claude and Ada Logics","type":"finder"},{"lang":"en","value":"Joshua Rogers (AISLE Research)","type":"reporter"},{"lang":"en","value":"Michael Niedermayer","type":"remediation developer"}],"x_generator":{"engine":"vulncheck-endgame"}}}}}