High severity · published Sep 13, 2026
CVE-2026-90783
MKVToolNix through 101.0 Heap Buffer Overflow via avilib ODML Superindex Integer Wraparound
7.8
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 10% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MK
MKVToolNix · Moritz Bunkus
through 101.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-90783
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-90783
patch
https://codeberg.org/mbunkus/mkvtoolnix/commit/1495126138e086080f0163bee27fafbdf956a1d0
technical-description
https://codeberg.org/mbunkus/mkvtoolnix/src/tag/release-101.0/lib/avilib-0.6.10/avilib.c#L2552-L2570
product
https://codeberg.org/mbunkus/mkvtoolnix
third-party-advisory
https://www.vulncheck.com/advisories/mkvtoolnix-through-101.0-heap-buffer-overflow-via-avilib-odml-superindex-integer-wraparound