{"id":"CVE-2026-125191","kind":"vulnerability","aliases":["CVE-2026-125191"],"related":[],"title":"FFmpeg: crafted video streams make the V4L2 decoder hang forever","description":"FFmpeg through 9.0.2 contains a reference count leak in libavcodec/v4l2_buffers.c that allows attackers to deadlock the V4L2 mem2mem decoder on multi-plane capture formats. Attackers can supply crafted H.264, HEVC, or VP9 streams with resolution changes, making ff_v4l2_m2m_codec_reinit() wait forever and hang the decoding application.","summary":"FFmpeg's V4L2 mem2mem decoder leaks a reference count in libavcodec/v4l2_buffers.c. A crafted H.264, HEVC, or VP9 stream with resolution changes makes the decoder wait forever, hanging the application that decodes it.","severity":"medium","cvss":5.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ffmpeg","libavcodec","linux","media-processing","package","v4l2"],"not_affected_if":["no-untrusted-input","software-decoding-only"],"how_to_check":"- Check whether the FFmpeg build includes the V4L2 mem2mem decoders (for example `ffmpeg -decoders | grep v4l2m2m`)\n- Check the FFmpeg version with `ffmpeg -version`; the sources say FFmpeg through 9.0.2 is affected\n- Check whether the application decodes untrusted video with hardware acceleration enabled","fix":"- FFmpeg: unknown; the sources do not name a fixed version\n- A patch is linked from the sources (github.com), but its content was not read","status":"open","published_at":"2026-11-09T19:16:54+00:00","first_seen_at":"2026-11-09T19:28:17+00:00","triaged_at":"2026-11-09T19:32:04+00:00","updated_at":"2026-11-09T19:32:04+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-09T19:32:04Z","model":"claude-haiku-5-5","output":{"fix":"- FFmpeg: unknown; the sources do not name a fixed version\n- A patch is linked from the sources (github.com), but its content was not read","reach":"internet","title":"FFmpeg: crafted video streams make the V4L2 decoder hang forever","impact":"low","summary":"FFmpeg's V4L2 mem2mem decoder leaks a reference count in libavcodec/v4l2_buffers.c. A crafted H.264, HEVC, or VP9 stream with resolution changes makes the decoder wait forever, hanging the application that decodes it.","audience":"developers","category":"package","nicknames":[],"who_cares":["ffmpeg","libavcodec","v4l2","linux","media-processing"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"Decoding application hangs indefinitely, causing denial of service","analyst_note":"Confirm the fixed FFmpeg version and the patch content from the linked github.com fix and the vulncheck advisory; the sources do not state a fix version.","how_to_check":"- Check whether the FFmpeg build includes the V4L2 mem2mem decoders (for example `ffmpeg -decoders | grep v4l2m2m`)\n- Check the FFmpeg version with `ffmpeg -version`; the sources say FFmpeg through 9.0.2 is affected\n- Check whether the application decodes untrusted video with hardware acceleration enabled","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["software-decoding-only","no-untrusted-input"],"who_is_affected":"Applications that decode video through FFmpeg's V4L2 mem2mem hardware decoders, especially ones that accept untrusted files or streams. A hang is a denial of service; the sources do not say code execution is possible. Programs that use only software decoding, or never receive untrusted media, are unlikely to be exposed.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000811,"input_tokens":4642,"output_tokens":693,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-125191':13A,16A '-2026':12A,15A '9.0.2':58C 'allow':67C 'applic':53B,105C 'attack':68C,81C 'captur':79C 'chang':45B,92C 'codec':97C 'contain':59C 'count':33B,62C 'craft':2A,37B,84C 'cve':11A,14A 'deadlock':70C 'decod':8A,29B,48B,55B,74C,104C 'ff':94C 'ffmpeg':1A,17B,25B,56C 'forev':10A,50B,100C 'format':80C 'h.264':38B,85C 'hang':9A,51B,102C 'hevc':39B,86C 'leak':30B,63C 'libavcodec':18B 'libavcodec/v4l2_buffers.c':35B,65C 'linux':19B 'm2m':96C 'make':5A,46B,93C 'media':21B 'media-process':20B 'mem2mem':28B,73C 'multi':77C 'multi-plan':76C 'packag':23B 'plane':78C 'process':22B 'refer':32B,61C 'reinit':98C 'resolut':44B,91C 'stream':4A,42B,89C 'suppli':83C 'v4l2':7A,24B,27B,72C,95C 'video':3A 'vp9':41B,88C 'wait':49B,99C","nicknames":[],"mitigations":[],"who_affected":"Applications that decode video through FFmpeg's V4L2 mem2mem hardware decoders, especially ones that accept untrusted files or streams. A hang is a denial of service; the sources do not say code execution is possible. Programs that use only software decoding, or never receive untrusted media, are unlikely to be exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"unknown","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["ffmpeg","libavcodec","linux","mediaprocessing","medium","package","v4l2"],"campaign_type":null,"search_a":"'-125191':13A,16A '-2026':12A,15A 'craft':2A 'cve':11A,14A 'decod':8A 'ffmpeg':1A 'forev':10A 'hang':9A 'make':5A 'stream':4A 'v4l2':7A 'video':3A","search_b":"'applic':53B 'chang':45B 'count':33B 'craft':37B 'decod':29B,48B,55B 'ffmpeg':17B,25B 'forev':50B 'h.264':38B 'hang':51B 'hevc':39B 'leak':30B 'libavcodec':18B 'libavcodec/v4l2_buffers.c':35B 'linux':19B 'make':46B 'media':21B 'media-process':20B 'mem2mem':28B 'packag':23B 'process':22B 'refer':32B 'resolut':44B 'stream':42B 'v4l2':24B,27B 'vp9':41B 'wait':49B","search_c":"'9.0.2':58C 'allow':67C 'applic':105C 'attack':68C,81C 'captur':79C 'chang':92C 'codec':97C 'contain':59C 'count':62C 'craft':84C 'deadlock':70C 'decod':74C,104C 'ff':94C 'ffmpeg':56C 'forev':100C 'format':80C 'h.264':85C 'hang':102C 'hevc':86C 'leak':63C 'libavcodec/v4l2_buffers.c':65C 'm2m':96C 'make':93C 'mem2mem':73C 'multi':77C 'multi-plan':76C 'plane':78C 'refer':61C 'reinit':98C 'resolut':91C 'stream':89C 'suppli':83C 'v4l2':72C,95C 'vp9':88C 'wait':99C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-09T19:16:54+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-125191","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-125191","severity":null,"published_at":"2026-11-09T19:16:54+00:00","modified_at":"2026-11-09T19:16:54+00:00","first_seen_at":"2026-11-09T19:28:17+00:00","fetched_at":"2026-11-09T19:28:17+00:00","note":null}],"documents":[{"id":109273,"url":"https://github.com/FFmpeg/FFmpeg/commit/4d2d58efa9b9f3802893b1db0ea1edfbe1cc66ef","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":109274,"url":"https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-v4l2-m2m-decoder-deadlock-via-reference-count-leak","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}