CVE-2026-120243: FFmpeg · Use of Uninitialized Variable
Affects FFmpegSource CVE Database V5
Not known to be exploited · CVSS 6.8 Medium.
Data as of 1 Nov 2026, 01:21 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 6.8 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 5.5 |
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 1 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| FFmpegFFmpeg | Affected
| Fixed in– |
GitHubFFmpegpkg:github/FFmpegOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users should monitor the FFmpeg project advisories for updates addressing this issue. Until a fix is available, avoid processing untrusted Go2Meeting (G2M3/G2M4) streams to mitigate the risk of memory disclosure. Since this is a local attack vector requiring user interaction, restricting access to trusted content and users can reduce exposure.
Description
CVE-2026-120243 is a vulnerability in FFmpeg versions 2.0 through 9.0.2 involving the use of an uninitialized variable in the Go2Meeting decoder. This flaw allows attackers to leak stack memory by exploiting out-of-range palette indices in crafted G2M3/G2M4 streams. The vulnerability arises because the function kempf_restore_buf() copies uninitialized stack bytes, potentially exposing sensitive data such as pointers or stack guards.
References
- code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24858 (opens in a new tab)
- github.com/FFmpeg/FFmpeg/commit/edad2d0dafcf44fa315eab716fd0183ce808053b (opens in a new tab)
- github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/g2meet.c (opens in a new tab)
- github.com/FFmpeg/FFmpeg (opens in a new tab)
- vulncheck.com/advisories/ffmpeg-2.0-through-9.0.2-information-disclosure-via-g2m-kempf-palette (opens in a new tab)