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Fencer Vulns
high 7.8

CVE-2026-90783 json

MKVToolNix through 101.0 Heap Buffer Overflow via avilib ODML Superindex Integer Wraparound

published 2026-09-13 56 d ago modified 2026-09-30 39 d ago also EUVD-2026-77010

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

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 cause an undersized heap allocation, allowing a heap buffer overflow when the file is parsed with mkvmerge.

Patch / fix

  • mkvtoolnix Debian 12 74.0.0-1+deb12u1
  • mkvtoolnix Debian 13 92.0-1+deb13u1
  • mkvtoolnix Debian 14 101.0-2

debian advisories DEBIAN-CVE-2026-90783

  • mkvtoolnix openSUSE Leap 16.0 95.0-bp160.2.1
  • mkvtoolnix openSUSE Tumbleweed 101.0-2.1

opensuse advisories openSUSE-SU-2026:21867-1openSUSE-SU-2026:11779-1

  • mkvtoolnix Alpine 3.24 99.0-r1

alpine advisories ALPINE-CVE-2026-90783

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-90783 updated cvss 7.8

mkvtoolnix: MKVToolNix: Heap buffer overflow in avilib when parsing malicious AVI files.

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
55 d ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 4.0 8.5 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.5 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • Moritz Bunkus MKVToolNix

Classification

Weakness
  • CWE-680 Integer Overflow to Buffer Overflow

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.