CVE-2026-125257
FFmpeg through 9.0.2 Heap Overflow via Nellymoser Encoder Trellis Search
Description
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.
INFO
Published Date :
Nov. 9, 2026, 8:18 p.m.
Last Modified :
Nov. 9, 2026, 8:18 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update FFmpeg to version 9.0.3 or later.
- Recompile applications using affected FFmpeg library.
- Avoid encoding with Nellymoser and trellis enabled.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-125257.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-125257 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-125257
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-125257 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-125257 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Nov. 09, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V4.0 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 Added CVSS V3.1 AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-193 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/125xxx/CVE-2026-125257.json">CVE-2026-125257</a> Added Reference https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24471 Added Reference https://github.com/FFmpeg/FFmpeg Added Reference https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/nellymoserenc.c#L262 Added Reference https://github.com/FFmpeg/FFmpeg/commit/733bec3e19759520ccdbeb6c3c0cae280bbe6dc5 Added Reference https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-overflow-via-nellymoser-encoder-trellis-search