Vulnerability DatabaseCVE-2026-125103
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CVE-2026-125103
Published:November 09, 2026
Updated:November 10, 2026
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.
Related Resources (8)
https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/125xxx/CVE-2026-125103.json
https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25703
https://github.com/FFmpeg/FFmpeg/commit/db98784a72600a94f7ebd5f016a37e01a505c27b
https://github.com/FFmpeg/FFmpeg
https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-uninitialized-heap-disclosure-via-mlz-decompressor-in-als-decoder
https://nvd.nist.gov/vuln/detail/CVE-2026-125103
https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/mlz.c#L161
https://code.ffmpeg.org/FFmpeg/FFmpeg
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CVSS v4
Base Score:
4.8
Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
3.3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Weakness Type (CWE)
Use of Uninitialized Resource
CWE-908