CVE-2026-121941: munt libmt32emu · Heap-based Buffer Overflow
Affects munt libmt32emuSource CVE Database V5
Not known to be exploited · CVSS 8.5 High : upgrade to 2.8.4 soon.
Data as of 4 Nov 2026, 12:59 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 8.5 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 7.8 |
- Patch
- Available – fixed in 2.8.4
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 4 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.
What to do
Upgrade munt libmt32emu to 2.8.4.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| muntlibmt32emu | Affected
| Fixed in
|
GitHublibmt32emupkg:github/libmt32emuOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade libmt32emu to version 2.8.4 or later, where this heap buffer overflow vulnerability is fixed. No other mitigation or temporary workaround is indicated by the vendor advisory.
Description
A heap-based buffer overflow vulnerability exists in libmt32emu versions before 2.8.4 in the MidiStreamParserImpl::parseSysex function. This flaw allows attackers to write beyond allocated heap memory by supplying oversized, unterminated SysEx messages exceeding 32768 bytes via the mt32emu_parse_stream API. Successful exploitation can corrupt heap memory and cause application crashes. The issue is fixed in version 2.8.4.
References
- github.com/munt/munt/issues/149 (opens in a new tab)
- hackmd.io/@haindpwn/munt-midistreamparser-oversized-sysex-heap-overflow (opens in a new tab)
- github.com/munt/munt/commit/1749f7fed5cdb3a9015acce076a1512b1615dc3b (opens in a new tab)
- github.com/munt/munt/blob/libmt32emu_2_8_3/mt32emu/src/MidiStreamParser.cpp (opens in a new tab)
- vulncheck.com/advisories/libmt32emu-before-2.8.4-heap-buffer-overflow-via-midistreamparserimpl-parsesysex (opens in a new tab)