{"id":"CVE-2026-125220","kind":"vulnerability","aliases":["CVE-2026-125220"],"related":[],"title":"FFmpeg: crafted Mimic video file hangs frame-threaded decoding indefinitely","description":"FFmpeg through 9.0.2 contains a deadlock vulnerability in mimic_decode_frame() in libavcodec/mimic.c that fails to report frame progress when init_get_bits8() fails. Attackers can supply a crafted file with an oversized Mimic intra frame followed by inter frames to hang frame-threaded decoding indefinitely.","summary":"FFmpeg's Mimic video decoder fails to report frame progress when a frame is oversized, which can deadlock frame-threaded decoding. An attacker who supplies a crafted file can make decoding hang indefinitely, a denial of service.","severity":"medium","cvss":6.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ffmpeg","media-processing","runtime","self-hosted"],"not_affected_if":["no-mimic-decoding","trusted-input-only"],"how_to_check":"- Check the FFmpeg version with `ffmpeg -version`; versions through `9.0.2` are described as affected.\n- Find services that decode untrusted media with FFmpeg, such as upload transcoders or thumbnail generators.","fix":null,"status":"open","published_at":"2026-11-09T19:16:59+00:00","first_seen_at":"2026-11-09T19:28:19+00:00","triaged_at":"2026-11-09T19:31:25+00:00","updated_at":"2026-11-09T19:31:25+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-11-09T19:31:25Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"unknown","title":"FFmpeg: crafted Mimic video file hangs frame-threaded decoding indefinitely","impact":"low","summary":"FFmpeg's Mimic video decoder fails to report frame progress when a frame is oversized, which can deadlock frame-threaded decoding. An attacker who supplies a crafted file can make decoding hang indefinitely, a denial of service.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["ffmpeg","media-processing","self-hosted"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"decoding hangs indefinitely, denying service to the process","analyst_note":"Confirm the fixed version and the patch from the linked GitHub commit and the VulnCheck advisory; the sources list no fixed version.","how_to_check":"- Check the FFmpeg version with `ffmpeg -version`; versions through `9.0.2` are described as affected.\n- Find services that decode untrusted media with FFmpeg, such as upload transcoders or thumbnail generators.","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["trusted-input-only","no-mimic-decoding"],"who_is_affected":"Systems that run FFmpeg to decode untrusted Mimic-format video, especially with frame threading enabled, are exposed to a hang. Systems that only process trusted media or do not decode Mimic files can skip it. The sources do not state a fixed version.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000743,"input_tokens":4624,"output_tokens":561,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-125220':14A,17A '-2026':13A,16A '9.0.2':66C 'attack':49B,88C 'bits8':86C 'contain':67C 'craft':2A,53B,92C 'cve':12A,15A 'deadlock':43B,69C 'decod':10A,30B,47B,57B,73C,109C 'denial':61B 'fail':31B,78C,87C 'ffmpeg':1A,18B,26B,64C 'file':5A,54B,93C 'follow':100C 'frame':8A,34B,38B,45B,74C,81C,99C,103C,107C 'frame-thread':7A,44B,106C 'get':85C 'hang':6A,58B,105C 'host':25B 'indefinit':11A,59B,110C 'init':84C 'inter':102C 'intra':98C 'libavcodec/mimic.c':76C 'make':56B 'media':20B 'media-process':19B 'mimic':3A,28B,72C,97C 'overs':40B,96C 'process':21B 'progress':35B,82C 'report':33B,80C 'runtim':22B 'self':24B 'self-host':23B 'servic':63B 'suppli':51B,90C 'thread':9A,46B,108C 'video':4A,29B 'vulner':70C","nicknames":[],"mitigations":[],"who_affected":"Systems that run FFmpeg to decode untrusted Mimic-format video, especially with frame threading enabled, are exposed to a hang. Systems that only process trusted media or do not decode Mimic files can skip it. The sources do not state a fixed version.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["ffmpeg","mediaprocessing","medium","runtime","selfhosted"],"campaign_type":null,"search_a":"'-125220':14A,17A '-2026':13A,16A 'craft':2A 'cve':12A,15A 'decod':10A 'ffmpeg':1A 'file':5A 'frame':8A 'frame-thread':7A 'hang':6A 'indefinit':11A 'mimic':3A 'thread':9A 'video':4A","search_b":"'attack':49B 'craft':53B 'deadlock':43B 'decod':30B,47B,57B 'denial':61B 'fail':31B 'ffmpeg':18B,26B 'file':54B 'frame':34B,38B,45B 'frame-thread':44B 'hang':58B 'host':25B 'indefinit':59B 'make':56B 'media':20B 'media-process':19B 'mimic':28B 'overs':40B 'process':21B 'progress':35B 'report':33B 'runtim':22B 'self':24B 'self-host':23B 'servic':63B 'suppli':51B 'thread':46B 'video':29B","search_c":"'9.0.2':66C 'attack':88C 'bits8':86C 'contain':67C 'craft':92C 'deadlock':69C 'decod':73C,109C 'fail':78C,87C 'ffmpeg':64C 'file':93C 'follow':100C 'frame':74C,81C,99C,103C,107C 'frame-thread':106C 'get':85C 'hang':105C 'indefinit':110C 'init':84C 'inter':102C 'intra':98C 'libavcodec/mimic.c':76C 'mimic':72C,97C 'overs':96C 'progress':82C 'report':80C 'suppli':90C 'thread':108C 'vulner':70C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-09T19:16:59+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/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-2026-125220","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-125220","severity":null,"published_at":"2026-11-09T19:16:59+00:00","modified_at":"2026-11-09T19:16:59+00:00","first_seen_at":"2026-11-09T19:28:19+00:00","fetched_at":"2026-11-09T19:28:19+00:00","note":null}],"documents":[{"id":109330,"url":"https://github.com/FFmpeg/FFmpeg/commit/db77b0b8318ddb38b5a3227724da088a325a4308","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":109331,"url":"https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-mimic-decoder-deadlock-via-frame-threading-failure","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"}