CVE-2026-120243 (CVSS 5.5)

Description

FFmpeg 2.0 through 9.0.2 contains a use of uninitialized variable vulnerability in the Go2Meeting decoder that allows attackers to leak stack memory through out-of-range palette indices. Attackers can craft a G2M3/G2M4 stream with a short Kempf palette so kempf_restore_buf() copies uninitialized stack bytes, including pointers or stack guards, into decoded output.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Weakness Type (CWE)

CWE-457 CWE-457

References

Other References

https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24858 https://github.com/FFmpeg/FFmpeg https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/g2meet.c#L1040-L1042 https://github.com/FFmpeg/FFmpeg/commit/edad2d0dafcf44fa315eab716fd0183ce808053b https://www.vulncheck.com/advisories/ffmpeg-2.0-through-9.0.2-information-disclosure-via-g2m-kempf-palette

Frequently Asked Questions

What is CVE-2026-120243? +

FFmpeg 2.0 through 9.0.2 contains a use of uninitialized variable vulnerability in the Go2Meeting decoder that allows attackers to leak stack memory through out-of-range palette indices. Attackers can craft a G2M3/G2M4 stream with a short Kempf palette so kempf_restore_buf() copies uninitialized stack bytes, including pointers or stack guards, into decoded output. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-120243? +

CVE-2026-120243 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-120243? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-120243