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.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| FFmpeg FFmpeg ffmpeg/ffmpeg
github |
≥ 0; ≤ 9.0.2 (affected, semver)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 7.3 high |
CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N | CNA: VulnCheck |
| 3.1 / 7.0 high |
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H | CNA: VulnCheck |
| 4.0 / 7.3 high |
CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD: [email protected] |
| 3.1 / 7.0 high |
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24471CNA: VulnCheck · issue-tracking
- https://github.com/FFmpeg/FFmpeg/commit/733bec3e19759520ccdbeb6c3c0cae280bbe6dc5CNA: VulnCheck · patch
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/nellymoserenc.c#L262CNA: VulnCheck · technical-description
- https://github.com/FFmpeg/FFmpegCNA: VulnCheck · product
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-overflow-via-nellymoser-encoder-trellis-searchCNA: VulnCheck · third-party-advisory
- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24471[email protected]
- https://github.com/FFmpeg/FFmpeg[email protected]
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/nellymoserenc.c#L262[email protected]
- https://github.com/FFmpeg/FFmpeg/commit/733bec3e19759520ccdbeb6c3c0cae280bbe6dc5[email protected]
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-overflow-via-nellymoser-encoder-trellis-search[email protected]
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