{"id":"CVE-2026-125226","kind":"vulnerability","aliases":["CVE-2026-125226"],"related":[],"title":"FFmpeg: crafted SBaGen script exhausts memory, causing denial of service","description":"FFmpeg through 9.0.2 contains an uncontrolled memory allocation vulnerability in sbg_read_header() in libavformat/sbgdec.c that derives an unbounded default frame size from the script's sample rate. Attackers can supply a crafted SBaGen script declaring a very high -r sample rate so the wavesynth decoder allocates enormous audio frames, exhausting memory and causing denial of service.","summary":"FFmpeg's SBaGen decoder derives an unbounded frame size from the script's sample rate, so a crafted script with a very high sample rate makes it allocate huge audio frames. An attacker can exhaust memory and crash the process.","severity":"medium","cvss":6.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ffmpeg","libavformat","media-processing","package"],"not_affected_if":["no-untrusted-input","sbagen-decoder-unused"],"how_to_check":"- Run `ffmpeg -version` to see whether the installed build is FFmpeg 9.0.2 or earlier.\n- Check whether the wavesynth/SBaGen decoder is enabled in the build (unknown from the sources whether it is on by default).","fix":null,"status":"open","published_at":"2026-11-09T19:17:00+00:00","first_seen_at":"2026-11-09T19:28:19+00:00","triaged_at":"2026-11-09T19:30:31+00:00","updated_at":"2026-11-09T19:30:31+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-09T19:30:31Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"unknown","title":"FFmpeg: crafted SBaGen script exhausts memory, causing denial of service","impact":"low","summary":"FFmpeg's SBaGen decoder derives an unbounded frame size from the script's sample rate, so a crafted script with a very high sample rate makes it allocate huge audio frames. An attacker can exhaust memory and crash the process.","audience":"developers","category":"package","nicknames":[],"who_cares":["ffmpeg","libavformat","media-processing"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"Memory exhaustion crashes the decoding process, causing denial of service","analyst_note":"Confirm the fixed FFmpeg version and whether the SBaGen decoder is enabled by default, using the linked patch on github.com and the vulncheck advisory.","how_to_check":"- Run `ffmpeg -version` to see whether the installed build is FFmpeg 9.0.2 or earlier.\n- Check whether the wavesynth/SBaGen decoder is enabled in the build (unknown from the sources whether it is on by default).","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["no-untrusted-input","sbagen-decoder-unused"],"who_is_affected":"Systems that run FFmpeg through 9.0.2 and decode SBaGen scripts from untrusted input are exposed. Systems that do not process untrusted SBaGen files, or that run a newer build, can skip it. The sources do not state a fixed version beyond a linked patch.","user_interaction":"unknown","product_ecosystem":"","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000757,"input_tokens":4634,"output_tokens":587,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-125226':13A,16A '-2026':12A,15A '9.0.2':65C 'alloc':50B,70C,109C 'attack':55B,91C 'audio':52B,111C 'caus':7A,116C 'contain':66C 'craft':2A,40B,95C 'crash':60B 'cve':11A,14A 'declar':98C 'decod':26B,108C 'default':82C 'denial':8A,117C 'deriv':27B,79C 'enorm':110C 'exhaust':5A,57B,113C 'ffmpeg':1A,17B,23B,63C 'frame':30B,53B,83C,112C 'header':75C 'high':45B,101C 'huge':51B 'libavformat':18B 'libavformat/sbgdec.c':77C 'make':48B 'media':20B 'media-process':19B 'memori':6A,58B,69C,114C 'packag':22B 'process':21B,62B 'r':102C 'rate':37B,47B,90C,104C 'read':74C 'sampl':36B,46B,89C,103C 'sbagen':3A,25B,96C 'sbg':73C 'script':4A,34B,41B,87C,97C 'servic':10A,119C 'size':31B,84C 'suppli':93C 'unbound':29B,81C 'uncontrol':68C 'vulner':71C 'wavesynth':107C","nicknames":[],"mitigations":[],"who_affected":"Systems that run FFmpeg through 9.0.2 and decode SBaGen scripts from untrusted input are exposed. Systems that do not process untrusted SBaGen files, or that run a newer build, can skip it. The sources do not state a fixed version beyond a linked patch.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["ffmpeg","libavformat","mediaprocessing","medium","package"],"campaign_type":null,"search_a":"'-125226':13A,16A '-2026':12A,15A 'caus':7A 'craft':2A 'cve':11A,14A 'denial':8A 'exhaust':5A 'ffmpeg':1A 'memori':6A 'sbagen':3A 'script':4A 'servic':10A","search_b":"'alloc':50B 'attack':55B 'audio':52B 'craft':40B 'crash':60B 'decod':26B 'deriv':27B 'exhaust':57B 'ffmpeg':17B,23B 'frame':30B,53B 'high':45B 'huge':51B 'libavformat':18B 'make':48B 'media':20B 'media-process':19B 'memori':58B 'packag':22B 'process':21B,62B 'rate':37B,47B 'sampl':36B,46B 'sbagen':25B 'script':34B,41B 'size':31B 'unbound':29B","search_c":"'9.0.2':65C 'alloc':70C,109C 'attack':91C 'audio':111C 'caus':116C 'contain':66C 'craft':95C 'declar':98C 'decod':108C 'default':82C 'denial':117C 'deriv':79C 'enorm':110C 'exhaust':113C 'ffmpeg':63C 'frame':83C,112C 'header':75C 'high':101C 'libavformat/sbgdec.c':77C 'memori':69C,114C 'r':102C 'rate':90C,104C 'read':74C 'sampl':89C,103C 'sbagen':96C 'sbg':73C 'script':87C,97C 'servic':119C 'size':84C 'suppli':93C 'unbound':81C 'uncontrol':68C 'vulner':71C 'wavesynth':107C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-09T19:17:00+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-2026-125226","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-125226","severity":null,"published_at":"2026-11-09T19:17:00+00:00","modified_at":"2026-11-09T19:17:00+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":109342,"url":"https://github.com/FFmpeg/FFmpeg/commit/1f4b2e22cfba19f94489ec4a17130f4f0d5d8a0c","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":109343,"url":"https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-excessive-memory-allocation-via-sbagen-demuxer","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"}