CVE-2026-90783
Received Received - Intake

Heap Buffer Overflow in MKVToolNix via AVI File Parsing

Publication date: 2026-09-13

Last updated on: 2026-09-13

Assigner: VulnCheck

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.

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Meta Information

Published
2026-09-13
Last Modified
2026-09-13
Generated
2026-09-13
AI Q&A
2026-09-13
EPSS Evaluated
N/A
NVD
CVE-2026-90783
EUVD
EUVD-2026-77010

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
mbunkus mkvtoolnix to 101.0 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-680 The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow.

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Executive Summary

MKVToolNix through version 101.0 has a heap buffer overflow in its bundled avilib library's ODML superindex parser. This happens due to integer wraparound in 32-bit arithmetic. Attackers can create a malicious AVI file with oversized entry counts, causing an undersized heap allocation. When mkvmerge parses this file, it leads to a heap buffer overflow.

Detection Guidance

Detecting this vulnerability requires checking for MKVToolNix versions up to 101.0 and scanning for malicious AVI files. Use commands like 'mkvmerge --version' to check installed versions. Scan files with 'file' or 'hexdump' to identify AVI files with oversized entry counts. Review logs for heap overflow errors during mkvmerge operations.

Impact Analysis

If you use MKVToolNix versions up to 101.0 to process untrusted AVI files, an attacker could exploit this flaw to execute arbitrary code on your system. This could lead to data theft, system compromise, or denial of service. The risk is higher if you handle files from untrusted sources.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches if exploited, potentially violating GDPR or HIPAA requirements for data protection. Organizations using affected MKVToolNix versions may face compliance risks if the flaw results in unauthorized data exposure or processing.

Mitigation Strategies

Immediately upgrade MKVToolNix to the latest patched version beyond 101.0. Remove or quarantine any untrusted AVI files. Disable parsing of AVI files in MKVToolNix if not required. Monitor systems for unusual activity or crashes during file processing.

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