FFmpeg through 9.0.2 VVC Decoder Heap Out-of-Bounds Write via refs.c
Affects 32-bit FFmpeg builds through 9.0.2 when decoding a crafted VVC (H.266) file with a very large number of NAL units per access unit. No fixed version is listed.
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 32-bit builds of FFmpeg through 9.0.2 Crafted VVC (H.266) file with a very large number of NAL units per access unit
- 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 versions up to 9.0.2 have a heap out-of-bounds write in the VVC decoder that is reached locally, without logging in, when a user opens a crafted VVC (H.266) file. An attacker who gets a victim to process such a file can corrupt memory, and this affects only 32-bit builds.
Read the original description
FFmpeg through 9.0.2 contains an integer overflow vulnerability in the VVC decoder alloc_frame() function in libavcodec/vvc/refs.c that undersizes the reference picture list allocation on 32-bit builds. Attackers can supply a crafted VVC (H.266) file with a very large number of NAL units per access unit to trigger heap out-of-bounds writes and corrupt memory.
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 32-bit builds of FFmpeg through 9.0.2 Crafted VVC (H.266) file with a very large number of NAL units per access unitApply 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-2026-125251
Is CVE-2026-125251 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?
A crafted VVC (H.266) file can trigger heap out-of-bounds writes that corrupt memory. The reference picture list allocation in refs.c is undersized on 32-bit builds, so the decoder writes past the end of it.Source: vulncheck.com
Which versions are affected by CVE-2026-125251?
FFmpeg: through 9.0.2.Source: cve.now feed data
Am I affected, and how do I check?
FFmpeg through version 9.0.2 is listed, and the issue is tied to 32-bit builds that decode VVC files with a very large number of NAL units per access unit. To check, run ffmpeg -version to get the version and confirm whether the build is 32-bit.Source: vulncheck.com
How do I fix CVE-2026-125251?
The checked facts do not name a fixed release or a vendor patch, so no upgrade target is available. Check the FFmpeg project for a release newer than 9.0.2 that addresses this issue.Source: vulncheck.com