FFmpeg through 9.0.2 Heap Buffer Overflow via ProRes prores_ks Encoder
Affects FFmpeg through 9.0.2 when the prores_ks encoder transcodes high-resolution video. The facts give no vendor rating or fixed version.
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 The prores_ks encoder is used to transcode the video The frame dimensions are large
- 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, a widely used multimedia library, has a heap buffer overflow in its ProRes prores_ks encoder that lets an attacker corrupt memory on a system where they can run the software locally. The attacker must get a user to process a crafted high-resolution video, which triggers an integer overflow in the frame size calculation and writes data past the end of an undersized buffer.
Read the original description
FFmpeg through 9.0.2 contains an integer overflow vulnerability in ff_prores_kostya_encode_init() that miscalculates frame_size_upper_bound using 32-bit arithmetic for large frame dimensions. Attackers can supply a high-resolution video transcoded with the prores_ks encoder, causing encode_frame() to write slices past an undersized packet buffer and corrupt heap memory.
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 The prores_ks encoder is used to transcode the video The frame dimensions are largeApply 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-2026-125259
Is CVE-2026-125259 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 prores_ks encoder handles large frames, 32-bit arithmetic causes encode_frame() to write slices past an undersized packet buffer. This corrupts heap memory.Source: vulncheck.com
Which versions are affected by CVE-2026-125259?
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. Check your version with ffmpeg -version, and check whether a transcode uses the prores_ks encoder (for example, -c:v prores_ks) on large frame dimensions.Source: vulncheck.com
How do I fix CVE-2026-125259?
No fixed version is listed in the checked facts, so no upgrade target can be named from them. Check FFmpeg's release notes or the vendor advisory for a release after 9.0.2 that addresses this issue.Source: vulncheck.com