FFmpeg through 9.0.2 Heap Corruption via libaribcaption ASS Error Cleanup
Affects FFmpeg through 9.0.2 when the libaribcaption ASS subtitle output path runs its error cleanup. No fixed version is listed in the facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fix or patch referenced
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Affects the libaribcaption ASS subtitle output path in FFmpeg through 9.0.2. A crafted caption has a later region that exceeds the 8 KiB AVBPrint limit. The error cleanup path runs, for example after an allocation failure while building the ASS rectangles.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 12/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FFmpeg through 9.0.2 contains an out-of-bounds read and invalid free vulnerability in aribcaption_trans_ass_subtitle() in libavcodec/libaribcaption.c that frees subtitle rectangles using region_count instead of num_rects. Attackers can supply crafted ARIB captions whose later region exceeds the 8 KiB AVBPrint limit, triggering cleanup that frees out-of-bounds pointers and corrupts the heap.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.3/10CVSS 7.3
- No patch0/5No signal
What would change the score
- Would score about 62 if added to CISA KEV
- Would score about 57 if CISA's SSVC rates exploitation active
- Would score about 22 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Affects the libaribcaption ASS subtitle output path in FFmpeg through 9.0.2. A crafted caption has a later region that exceeds the 8 KiB AVBPrint limit. The error cleanup path runs, for example after an allocation failure while building the ASS rectangles.Apply the patch listed under Evidence.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- FFmpeg FFmpeg
through 9.0.2
Evidence 5
- Patch
- Report
- Repository
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-125211
Is CVE-2026-125211 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
When the libaribcaption ASS subtitle path hits an error, its cleanup frees the wrong number of subtitle rectangles, including pointers past the end of the array. This can read out of bounds and free invalid pointers, which corrupts the heap.Source: code.ffmpeg.org, vulncheck.com, github.com
Which versions are affected by CVE-2026-125211?
FFmpeg: through 9.0.2.Source: cve.now feed data
Am I affected, and how do I check?
FFmpeg versions through 9.0.2 are listed as affected. The bug needs a build with libaribcaption and the ASS subtitle output path, and the error cleanup must run, for example after an allocation failure while building the ASS rectangles or when a caption region exceeds the 8 KiB AVBPrint limit. To check, run ffmpeg -version for the version and ffmpeg -buildconf to see whether libaribcaption is enabled.Source: code.ffmpeg.org, vulncheck.com, github.com
How do I fix CVE-2026-125211?
The facts do not name a fixed release, so no upgrade target can be given here. Check the FFmpeg project's advisory or release notes for a patched version, and until one is confirmed, limit exposure as described in the advisory.Source: code.ffmpeg.org, vulncheck.com, github.com