---
id: CVE-2026-90783
title: >-
  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
summary: >-
  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 cau…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-680
vendor: Moritz Bunkus
product: MKVToolNix
affected:
  - MKVToolNix <= 101.0
published: '2026-09-13'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T20:43:32.537'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90783'
references:
  - url: 'https://codeberg.org/mbunkus/mkvtoolnix'
    label: disclosure@vulncheck.com
  - url: >-
      https://codeberg.org/mbunkus/mkvtoolnix/commit/1495126138e086080f0163bee27fafbdf956a1d0
    label: disclosure@vulncheck.com
  - url: >-
      https://codeberg.org/mbunkus/mkvtoolnix/src/tag/release-101.0/lib/avilib-0.6.10/avilib.c#L2552-L2570
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/mkvtoolnix-through-101.0-heap-buffer-overflow-via-avilib-odml-superindex-integer-wraparound
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90783.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-90783'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-90783'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00202
epssPercentile: 0.08921
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-14T17:32:46.690815Z'
ingestedAt: '2026-09-14T15:23:07.470Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90783.json)