Medium
Security advisory
A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU via a crafted video file in Matroska format, because handle_open_brace in libavcodec/htmlsubtitles.c has a complex format argument to sscanf.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2019-9721
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:20 UTC · Revision 1
Source evidence
A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU via a crafted video file in Matroska format, because handle_open_brace in libavcodec/htmlsubtitles.c has a complex format argument to sscanf.
osv:CVE-2019-9721
Complete source record
{
"id": "3004cf0d1c364f1276b71a2a263378bfb60120b05bff1716cad6621862a3e50e",
"url": "https://osv.dev/vulnerability/CVE-2019-9721",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2019-9721",
"summary": "A denial of service in the subtitle decoder in FFmpeg 3.2 and 4.1 allows attackers to hog the CPU via a crafted video file in Matroska format, because handle_open_brace in libavcodec/htmlsubtitles.c has a complex format argument to sscanf.",
"evidence": "osv:CVE-2019-9721",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2019-9721",
"aliases": [
"CVE-2019-9721"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://git.ffmpeg.org/ffmpeg.git",
"type": "GIT",
"events": [
{
"introduced": "340cea9f22c162e10d120835661e132721b7454b"
},
{
"last_affected": "3c1ecb057d7621e57968624aa15ad3e9efc819f7"
},
{
"fixed": "894995c41e0795c7a44f81adc4838dedc3932e65"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:ffmpeg:ffmpeg:3.2:*:*:*:*:*:*:*",
"range": [
{
"introduced": "3.2"
},
{
"last_affected": "3.2"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:ffmpeg:ffmpeg:4.1:*:*:*:*:*:*:*",
"range": [
{
"introduced": "4.1"
},
{
"last_affected": "4.1"
}
],
"source": "CPE_STRING"
},
{
"range": [
{
"fixed": "894995c41e0795c7a44f81adc4838dedc3932e65"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"3.2",
"4.1",
"n4.1-dev",
"n3.5-dev",
"n3.4-dev",
"n3.3-dev",
"n3.2-dev"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2019-9721.json",
"vanir_signatures": [
{
"id": "CVE-2019-9721-db6040e3",
"digest": {
"threshold": 0.9,
"line_hashes": [
"181052376676104601782979859616773957010",
"114335331683057061847747733341231002884",
"52182576610393413327815494532710655027",
"151988408299784471571915177291850664201",
"205800561400509182498662806663250084866",
"276078855066844007631535584051836444593",
"154285558137714227043646505153518954530",
"291842367137479557043398546324464656376",
"258470655490914664899790479643506909951",
"315927009099581820947690650327589782134",
"208572855481831454275286035163998736879",
"168711716481488611153412673907818853193"
]
},
"source": "https://git.ffmpeg.org/ffmpeg.git@894995c41e0795c7a44f81adc4838dedc3932e65",
"target": {
"file": "libavcodec/htmlsubtitles.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
},
{
"id": "CVE-2019-9721-ff8fb535",
"digest": {
"length": 499,
"function_hash": "279534106679732723151319424601863156938"
},
"source": "https://git.ffmpeg.org/ffmpeg.git@894995c41e0795c7a44f81adc4838dedc3932e65",
"target": {
"file": "libavcodec/htmlsubtitles.c",
"function": "handle_open_brace"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-24T14:13:12Z"
}
},
{
"ranges": [
{
"repo": "https://github.com/ffmpeg/ffmpeg",
"type": "GIT",
"events": [
{
"introduced": "340cea9f22c162e10d120835661e132721b7454b"
},
{
"last_affected": "3c1ecb057d7621e57968624aa15ad3e9efc819f7"
},
{
"fixed": "273f2755ce8635d42da3cde0eeba15b2e7842774"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:ffmpeg:ffmpeg:3.2:*:*:*:*:*:*:*",
"range": [
{
"introduced": "3.2"
},
{
"last_affected": "3.2"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:ffmpeg:ffmpeg:4.1:*:*:*:*:*:*:*",
"range": [
{
"introduced": "4.1"
},
{
"last_affected": "4.1"
}
],
"source": "CPE_STRING"
},
{
"range": [
{
"fixed": "273f2755ce8635d42da3cde0eeba15b2e7842774"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"3.2",
"4.1",
"n3.2.13",
"n3.2.12",
"n3.2.11",
"n4.1-dev",
"n3.2.10",
"n3.2.9",
"n3.5-dev",
"n3.2.8",
"n3.2.7",
"n3.2.6",
"n3.2.5",
"n3.4-dev",
"n3.2.4",
"n3.2.3",
"n3.2.2",
"n3.2.1",
"n3.2",
"n3.3-dev",
"n3.2-dev"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2019-9721.json",
"vanir_signatures": [
{
"id": "CVE-2019-9721-1e4b4ede",
"digest": {
"length": 3610,
"function_hash": "51195086334001458191859035190219042570"
},
"source": "https://github.com/ffmpeg/ffmpeg/commit/273f2755ce8635d42da3cde0eeba15b2e7842774",
"target": {
"file": "libavcodec/htmlsubtitles.c",
"function": "ff_htmlmarkup_to_ass"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CVE-2019-9721-efb6ae89",
"digest": {
"threshold": 0.9,
"line_hashes": [
"181052376676104601782979859616773957010",
"114335331683057061847747733341231002884",
"52182576610393413327815494532710655027",
"151988408299784471571915177291850664201",
"143530476180291881434987183528048468203",
"20671168889515778463202263099394878314",
"117734745311139794259276495167403311113",
"247691314197916473622205852293270336349",
"91970035849042864838408869607449612939",
"298548214798456625181670453837162301144",
"51594798183235078235674705393957355135",
"244888744203267073148994254791264550488"
]
},
"source": "https://github.com/ffmpeg/ffmpeg/commit/273f2755ce8635d42da3cde0eeba15b2e7842774",
"target": {
"file": "libavcodec/htmlsubtitles.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-24T14:13:12Z"
}
}
],
"modified": "2026-10-24T14:13:12.402180198Z",
"provider": "osv",
"references": [
"https://usn.ubuntu.com/3967-1/",
"https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/894995c41e0795c7a44f81adc4838dedc3932e65",
"https://github.com/FFmpeg/FFmpeg/commit/273f2755ce8635d42da3cde0eeba15b2e7842774"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*",
"cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*"
],
"vendor_product": "canonical:ubuntu_linux",
"extracted_events": [
{
"range": [
{
"introduced": "18.04"
},
{
"last_affected": "18.04"
},
{
"introduced": "18.10"
},
{
"last_affected": "18.10"
},
{
"introduced": "19.04"
},
{
"last_affected": "19.04"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2019-9721",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 443427,
"published_at": "2019-03-12T09:29:00.577+00:00"
}