FFmpeg through 9.0.2 Out-of-Bounds Memory Access in Huffyuv/FFVHUFF Median Predictor
FFmpeg through 9.0.2 is affected when its Huffyuv or FFVHUFF encoder uses the median predictor on very small frames. No fix is listed in the checked 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. FFmpeg through 9.0.2 is affected Huffyuv or FFVHUFF encoder using the median predictor Frame is very small, such as 2 pixels wide or 1-2 pixels tall
- 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? →
- 14/100 · 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 memory access vulnerability in the encode_frame() function of libavcodec/huffyuvenc.c, because encode_init() never validates minimum frame dimensions for the median predictor. Attackers can supply a tiny video, such as a 2-pixel-wide or 1-2-pixel-tall frame, that causes negative sub_median_pred lengths and out-of-bounds reads and writes when transcoded to huffyuv or ffvhuff, crashing the encoder.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.5/10CVSS 8.5
- No patch0/5No signal
What would change the score
- Would score about 64 if added to CISA KEV
- Would score about 59 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
FFmpeg through 9.0.2 is affected Huffyuv or FFVHUFF encoder using the median predictor Frame is very small, such as 2 pixels wide or 1-2 pixels tallApply 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.
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Questions about CVE-2026-125229
Is CVE-2026-125229 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?
Encoding a very small frame with the Huffyuv or FFVHUFF encoder using the median predictor causes out-of-bounds memory reads and writes that crash the encoder. The cause is that encode_init() never validates minimum frame dimensions for the median predictor.Source: vulncheck.com
Which versions are affected by CVE-2026-125229?
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 affected. The setup involves the Huffyuv or FFVHUFF encoder with the median predictor and frames as small as 2 pixels wide or 1-2 pixels tall. Check your FFmpeg version with ffmpeg -version and check whether your encode command uses the huffyuv or ffvhuff video codec with the median predictor.Source: vulncheck.com
How do I fix CVE-2026-125229?
The checked facts name no fixed version, so no upgrade target can be given. Check the FFmpeg project for a release later than 9.0.2 that addresses this issue.Source: vulncheck.com