Vulnerability · Published Nov 4, 2026 · Assigned by VulnCheck

CVE-2026-121941libmt32emu before 2.8.4 Heap Buffer Overflow via MidiStreamParserImpl::parseSysex

High 7.8

In plain English

A high-severity heap buffer overflow in libmt32emu from munt. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities).

Severity (CVSS 3.1)7.8High

Exploit odds (30 days)0.3%top 82.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 products (as reported)

Vendor	Product	Versions
munt	libmt32emu	0 – before 2.8.4

Weakness: CWE-122 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

References

https://github.com/munt/munt/issues/149 issue-tracking
https://hackmd.io/@haindpwn/munt-midistreamparser-oversized-sysex-heap-overflow third-party-advisory
https://github.com/munt/munt/commit/1749f7fed5cdb3a9015acce076a1512b1615dc3b patch
https://github.com/munt/munt/blob/libmt32emu_2_8_3/mt32emu/src/MidiStreamParser.cpp#L223-L257 technical-description
VulnCheck Advisory: libmt32emu before 2.8.4 Heap Buffer Overflow via MidiStreamParserImpl::parseSysex third-party-advisory
https://hackmd.io/@haindpwn/cve-2026-121941-munt-midistreamparser-oversized-sysex-heap-overflow exploit