{"id":"UBUNTU-CVE-2026-66038","details":"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.","modified":"2026-09-10T00:56:42.552997591Z","published":"2026-07-24T20:18:00Z","related":["USN-8671-1","USN-8738-1"],"upstream":["CVE-2026-66038"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-66038"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-66038"},{"type":"REPORT","url":"https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23626"},{"type":"REPORT","url":"https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/e7cbfd1c507b57a806a5825b87d609963e862c8c"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/ffmpeg-lcl-zlib-video-decoder-information-disclosure-via-lcldec-c"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8671-1"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8738-1"}],"affected":[{"package":{"name":"libav","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/libav?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6:0.8.7-1ubuntu2","6:9.10-1ubuntu1","6:9.10-1ubuntu2","6:9.10-1ubuntu5","6:9.10-1ubuntu6","6:9.10-1ubuntu7","6:9.11-2ubuntu1","6:9.11-2ubuntu2","6:9.13-0ubuntu0.14.04.1","6:9.14-0ubuntu0.14.04.1","6:9.16-0ubuntu0.14.04.1","6:9.18-0ubuntu0.14.04.1","6:9.20-0ubuntu0.14.04.1","6:9.20-0ubuntu0.14.04.1+esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libav-tools"},{"binary_name":"libavcodec-extra","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_name":"libavcodec-extra-54","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libavcodec54"},{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libavdevice-extra-53"},{"binary_name":"libavdevice53","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_name":"libavfilter-extra-3","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libavfilter3"},{"binary_name":"libavformat-extra-54","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libavformat54"},{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libavresample1"},{"binary_name":"libavutil-extra-52","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_name":"libavutil52","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"},{"binary_version":"6:9.20-0ubuntu0.14.04.1+esm1","binary_name":"libswscale-extra-2"},{"binary_name":"libswscale2","binary_version":"6:9.20-0ubuntu0.14.04.1+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-66038.json"}},{"package":{"name":"ffmpeg","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7:2.8.17-0ubuntu0.1+esm15"}]}],"versions":["7:2.7.2-1build1","7:2.8.1-1ubuntu1","7:2.8.2-1ubuntu1","7:2.8.3-1","7:2.8.4-1","7:2.8.4-1ubuntu1","7:2.8.4-1ubuntu2","7:2.8.4-1ubuntu3","7:2.8.4-1ubuntu4","7:2.8.6-1ubuntu1","7:2.8.6-1ubuntu2","7:2.8.8-0ubuntu0.16.04.1","7:2.8.10-0ubuntu0.16.04.1","7:2.8.11-0ubuntu0.16.04.1","7:2.8.14-0ubuntu0.16.04.1","7:2.8.15-0ubuntu0.16.04.1","7:2.8.15-0ubuntu0.16.04.1+esm1","7:2.8.17-0ubuntu0.1","7:2.8.17-0ubuntu0.1+esm1","7:2.8.17-0ubuntu0.1+esm2","7:2.8.17-0ubuntu0.1+esm3","7:2.8.17-0ubuntu0.1+esm4","7:2.8.17-0ubuntu0.1+esm5","7:2.8.17-0ubuntu0.1+esm6","7:2.8.17-0ubuntu0.1+esm7","7:2.8.17-0ubuntu0.1+esm8","7:2.8.17-0ubuntu0.1+esm9","7:2.8.17-0ubuntu0.1+esm10","7:2.8.17-0ubuntu0.1+esm11","7:2.8.17-0ubuntu0.1+esm12","7:2.8.17-0ubuntu0.1+esm13","7:2.8.17-0ubuntu0.1+esm14"],"ecosystem_specific":{"binaries":[{"binary_name":"ffmpeg","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libav-tools","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libavcodec-extra","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libavcodec-ffmpeg-extra56","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libavcodec-ffmpeg56","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_version":"7:2.8.17-0ubuntu0.1+esm15","binary_name":"libavdevice-ffmpeg56"},{"binary_name":"libavfilter-ffmpeg5","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libavformat-ffmpeg56","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libavresample-ffmpeg2","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libavutil-ffmpeg54","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libpostproc-ffmpeg53","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_name":"libswresample-ffmpeg1","binary_version":"7:2.8.17-0ubuntu0.1+esm15"},{"binary_version":"7:2.8.17-0ubuntu0.1+esm15","binary_name":"libswscale-ffmpeg3"}],"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-66038.json"}},{"package":{"name":"ffmpeg","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/ffmpeg?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7:3.4.11-0ubuntu0.1+esm13"}]}],"versions":["7:3.3.4-2","7:3.3.4-2build3","7:3.4-2ubuntu2","7:3.4-4","7:3.4-4build1","7:3.4.1-1","7:3.4.1-1build1","7:3.4.2-1","7:3.4.2-1build1","7:3.4.2-2","7:3.4.4-0ubuntu0.18.04.1","7:3.4.6-0ubuntu0.18.04.1","7:3.4.8-0ubuntu0.2","7:3.4.11-0ubuntu0.1","7:3.4.11-0ubuntu0.1+esm1","7:3.4.11-0ubuntu0.1+esm2","7:3.4.11-0ubuntu0.1+esm3","7:3.4.11-0ubuntu0.1+esm4","7:3.4.11-0ubuntu0.1+esm5","7:3.4.11-0ubuntu0.1+esm6","7:3.4.11-0ubuntu0.1+esm7","7:3.4.11-0ubuntu0.1+esm8","7:3.4.11-0ubuntu0.1+esm9","7:3.4.11-0ubuntu0.1+esm10","7:3.4.11-0ubuntu0.1+esm11","7:3.4.11-0ubuntu0.1+esm12"],"ecosystem_specific":{"binaries":[{"binary_version":"7:3.4.11-0ubuntu0.1+esm13","binary_name":"ffmpeg"},{"binary_name":"libavcodec-extra","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_version":"7:3.4.11-0ubuntu0.1+esm13","binary_name":"libavcodec-extra57"},{"binary_name":"libavcodec57","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_version":"7:3.4.11-0ubuntu0.1+esm13","binary_name":"libavdevice57"},{"binary_name":"libavfilter-extra","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_name":"libavfilter-extra6","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_name":"libavfilter6","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_name":"libavformat57","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_name":"libavresample3","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_version":"7:3.4.11-0ubuntu0.1+esm13","binary_name":"libavutil55"},{"binary_version":"7:3.4.11-0ubuntu0.1+esm13","binary_name":"libpostproc54"},{"binary_name":"libswresample2","binary_version":"7:3.4.11-0ubuntu0.1+esm13"},{"binary_name":"libswscale4","binary_version":"7:3.4.11-0ubuntu0.1+esm13"}],"availability":"Available with Ubuntu Pro: 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with Ubuntu Pro: 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with Ubuntu Pro: 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with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-66038.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"},{"type":"CVSS_V4","score":"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"},{"type":"Ubuntu","score":"medium"}]}