What’s Vulnerable › Vulnerabilities

CVE-2026-90783: MKVToolNix through 101.0 Heap Buffer Overflow via avilib ODML Superindex Integer Wraparound

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-13 · updated 2026-09-30
• Weakness: CWE-680

Description

MKVToolNix through 101.0 contains a heap buffer overflow in the bundled avilib library's ODML superindex parser due to integer wraparound in 32-bit arithmetic. Attackers can craft a malicious AVI file with oversized entry counts that cause an undersized heap allocation, allowing a heap buffer overflow when the file is parsed with mkvmerge.

Affected products

• Moritz Bunkus MKVToolNix: through 101.0

References

• https://codeberg.org/mbunkus/mkvtoolnix
• https://codeberg.org/mbunkus/mkvtoolnix/commit/1495126138e086080f0163bee27fafbdf956a1d0
• https://codeberg.org/mbunkus/mkvtoolnix/src/tag/release-101.0/lib/avilib-0.6.10/avilib.c#L2552-L2570
• https://www.vulncheck.com/advisories/mkvtoolnix-through-101.0-heap-buffer-overflow-via-avilib-odml-superindex-integer-wraparound
• https://lists.debian.org/debian-lts-announce/2026/09/msg00040.html

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