CVSS 4.0
5.7 mediumCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NCVE-2026-125246 ffmpeg ffmpeg: Reachable Assertion
Medium (5.7) in ffmpeg ffmpeg. EPSS 0.2% estimated probability of exploitation activity in the next 30 days.
On this page
FFmpeg through 9.0.2 contains a denial of service vulnerability in cbs_jpeg_assemble_fragment() that miscounts 0xff stuffing bytes in JPEG scan headers. Attackers can supply a crafted JPEG/MJPEG stream with 0xff in the scan header, triggering an av_assert0 abort when CBS-based bitstream filters process it.
Severity
CVSS 3.1
4.7 mediumCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H- EPSS
- 0.2% estimated probability of exploitation activity in the next 30 days; 5th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: no · Technical impact: partial, assessed 2026-11-09. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-617 Reachable Assertion
- Published
- Modified
- Assigned by
- VulnCheck (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
Ask an AI about this CVE
Show the prompt
Explain CVE-2026-125246 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-125246?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-125246?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-125246 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
Badge for a README or a site
An image that stays current: it is drawn from the data each time it is fetched (a host that proxies images, as GitHub does, may show its copy for a while). Markdown:
[](https://cve.bz/cve/CVE-2026-125246)
HTML:
<a href="https://cve.bz/cve/CVE-2026-125246"><img src="https://cve.bz/cve/badge/CVE-2026-125246.svg" alt="CVE-2026-125246"></a>
Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| FFmpeg | through 9.0.2 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Ubuntu | 26.10, Pro:16.04:LTS, Pro:18.04:LTS and 4 more | ffmpeg | no fix listed | UBUNTU-CVE-2026-125246 |
From the distributions' data via OSV.dev: Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Ubuntu.
References
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25232
- https://github.com/FFmpeg/FFmpeg
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cbs_jpeg.c#L365
- https://github.com/FFmpeg/FFmpeg/commit/ee457fdcdb3a069ef35910a2e1cacff10906b131
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-assertion-failure-dos-via-cbs-jpeg-assemble-fragment