CVE-2026-125103

FFmpeg through 9.0.2 Uninitialized Heap Disclosure via MLZ Decompressor in ALS Decoder

Published Nov 9, 2026 CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed
Description
FFmpeg through 9.0.2 contains an information disclosure vulnerability in ff_mlz_decompression() in libavcodec/mlz.c, which accepts string codes beyond the dictionary's next free code. Attackers can supply a crafted MPEG-4 ALS file with malformed initial or out-of-range codes to copy uninitialized heap bytes into decoded audio output.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description FFmpeg through 9.0.2 contains an information disclosure vulnerability in ff_mlz_decompression() in libavcodec/mlz.c, which accepts string codes beyond the dictionary's next free code. Attackers can supply a crafted MPEG-4 ALS file with malformed initial or out-of-range codes to copy uninitialized heap bytes into decoded audio output.
Title FFmpeg through 9.0.2 Uninitialized Heap Disclosure via MLZ Decompressor in ALS Decoder
First Time appeared Ffmpeg
Ffmpeg ffmpeg
Weaknesses CWE-908
CPEs cpe:2.3:a:ffmpeg:ffmpeg:*:*:*:*:*:*:*:*
Vendors & Products Ffmpeg
Ffmpeg ffmpeg
References
Metrics cvssV3_1

{'score': 3.3, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'}

cvssV4_0

{'score': 4.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 10, 2026, 3:47 PM
Reserved
Nov 9, 2026, 5:44 PM
Status
Awaiting Analysis
Published
Nov 9, 2026, 7:16 PM
Modified
Nov 10, 2026, 9:46 PM