FFmpeg through 9.0.2 Heap Buffer Overflow in libwebp Encoder Conditional Replenishment
Affects FFmpeg through 9.0.2 when the libwebp encoder's cr_threshold option is set and the input resolution increases mid-stream. No fixed version 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. The cr_threshold option is set (libwebp encoder conditional replenishment). The input media's resolution increases mid-stream.
- 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 a heap buffer overflow in ff_libwebp_get_frame() in libwebpenc_common.c that lets attackers corrupt memory when cr_threshold is set. Attackers can supply crafted media that increases resolution mid-stream, causing memcpy() to write pixel data past the stale reference frame and crash applications.
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.
The cr_threshold option is set (libwebp encoder conditional replenishment). The input media's resolution increases mid-stream.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.
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Questions about CVE-2026-125204
Is CVE-2026-125204 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?
The libwebp encoder in FFmpeg can write pixel data past the end of a reference frame buffer, which corrupts memory and can crash applications. The overflow happens when the cr_threshold option is set and the input resolution increases mid-stream.Source: vulncheck.com
Which versions are affected by CVE-2026-125204?
FFmpeg: through 9.0.2.Source: cve.now feed data
Am I affected, and how do I check?
FFmpeg versions up to and including 9.0.2 are listed as affected. The bug needs the libwebp encoder with the cr_threshold option set and a stream whose resolution increases mid-stream, so check whether cr_threshold appears in the encoder options used with the ffmpeg command or in the application's FFmpeg settings.Source: vulncheck.com
How do I fix CVE-2026-125204?
The checked facts do not name a fixed FFmpeg version, so no upgrade target can be confirmed from them. Check the FFmpeg project's advisory or release notes for a patched release before relying on any version.Source: vulncheck.com