CVE-2026-125257
FFmpeg through 9.0.2 Heap Overflow via Nellymoser Encoder Trellis Search
FFmpeg through 9.0.2 contains an off-by-one heap overflow vulnerability in get_exponent_dynamic() in libavcodec/nellymoserenc.c that allows writing one element past the opt and path allocations. Attackers can supply crafted audio to applications encoding Nellymoser with trellis enabled, causing idx to equal OPT_SIZE and overwrite adjacent heap memory.
Public vulnerability details
- Record state
- Published
- Published (UTC)
- Last updated (UTC)
- Assigned by
- VulnCheck
- CVSS score
- 7.3 (CVSS v4.0, from VulnCheck)
- Severity
- HIGH
- CISA KEV
- No KEV entry in this record. This does not show that the CVE is absent from the KEV catalog.
- Additional data from
- None
FHE assessment
No FHE assessment is available in this application yet. This does not mean FHE cannot mitigate an impact of this CVE.
References
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24471 (VulnCheck)
- Patch Commit (VulnCheck)
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/nellymoserenc.c#L262 (VulnCheck)
- https://github.com/FFmpeg/FFmpeg (VulnCheck)
- VulnCheck Advisory: FFmpeg through 9.0.2 Heap Overflow via Nellymoser Encoder Trellis Search (VulnCheck)
Source
CVE JSON 5.2 record from the CVE List archive 2026-11-09_delta_CVEs_at_end_of_day.zip, which covers changes through . Imported .