---
id: CVE-2026-121941
title: >-
  libmt32emu before 2.8.4 Heap Buffer Overflow via
  MidiStreamParserImpl::parseSysex
summary: >-
  libmt32emu before 2.8.4 contains a heap buffer overflow vulnerability in
  MidiStreamParserImpl::parseSysex that allows attackers to write past a heap
  allocation by supplying oversized unterminated SysEx messages. Attackers can
  feed more t…
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'
cvssSource: cna
cwe:
  - CWE-122
vendor: munt
product: libmt32emu
affected:
  - libmt32emu < 2.8.4
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-04T20:17:29.860940Z'
exploitAvailable: true
published: '2026-11-04'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T20:18:07.407Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-121941'
references:
  - url: 'https://github.com/munt/munt/issues/149'
  - url: >-
      https://hackmd.io/@haindpwn/munt-midistreamparser-oversized-sysex-heap-overflow
  - url: >-
      https://github.com/munt/munt/commit/1749f7fed5cdb3a9015acce076a1512b1615dc3b
  - url: >-
      https://github.com/munt/munt/blob/libmt32emu_2_8_3/mt32emu/src/MidiStreamParser.cpp#L223-L257
  - url: >-
      https://www.vulncheck.com/advisories/libmt32emu-before-2.8.4-heap-buffer-overflow-via-midistreamparserimpl-parsesysex
    label: >-
      VulnCheck Advisory: libmt32emu before 2.8.4 Heap Buffer Overflow via
      MidiStreamParserImpl::parseSysex
tags:
  - cve.org
  - exploit-available
ingestedAt: '2026-11-05T21:36:00.536Z'
epss: 0.0026
epssPercentile: 0.17836
---

## Overview

libmt32emu before 2.8.4 contains a heap buffer overflow vulnerability in MidiStreamParserImpl::parseSysex that allows attackers to write past a heap allocation by supplying oversized unterminated SysEx messages. Attackers can feed more than 32768 SysEx data bytes through the mt32emu_parse_stream API via MIDI files, ports, or sequencer clients to corrupt heap memory and crash the application.

## Affected

- `libmt32emu < 2.8.4`

## Remediation

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