CVE-2026-120246

MEDIUM 5.5

FFmpeg 4.4 through 9.0.2 Uninitialized Memory Disclosure via CDXL HAM Decoder

CVSS Score

5.5

EPSS Score

0.0%

EPSS Percentile

0th

FFmpeg 4.4 through 9.0.2 contains a use of uninitialized variable vulnerability in the CDXL decoder that leaks stack memory into decoded pixels via unfilled HAM palette entries. Attackers can craft a type-0 CDXL file whose HAM pixels select unfilled new_palette entries in cdxl_decode_ham8() or cdxl_decode_ham6(), exposing stack bytes and pointer fragments in the BGR24 output.

CWE	CWE-457
Vendor	ffmpeg
Product	ffmpeg
Published	Nov 1, 2026

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CVSS v3 Breakdown

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

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Affected Versions

FFmpeg / FFmpeg

4.4 ≤ 9.0.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

code.ffmpeg.org: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24856 github.com: https://github.com/FFmpeg/FFmpeg/commit/47313ad3f9f33b892384b976fb7c09b3c85fd74e github.com: https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cdxl.c#L226-L229 github.com: https://github.com/FFmpeg/FFmpeg vulncheck.com: https://www.vulncheck.com/advisories/ffmpeg-4.4-through-9.0.2-uninitialized-memory-disclosure-via-cdxl-ham-decoder

Credits

Adrian Junge (vurlo)