CVE-2026-121941 json
libmt32emu before 2.8.4 Heap Buffer Overflow via MidiStreamParserImpl::parseSysex
published 5d ago modified 5d ago also EUVD-2026-116898
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 17%
- public exploits
- 0
- none known
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 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.
Patch / fix
Is CVE-2026-121941 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 5d ago
Exploit prediction
0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- hackmd.io https://hackmd.io/@haindpwn/cve-2026-121941-munt-midistreamparser-oversized-sysex-heap-overflow referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| 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 | 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/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
- munt libmt32emu
Classification
- Weakness
-
- CWE-122 Heap-based Buffer Overflow
References
-
github.com
/munt/munt/commit/1749f7fed5cdb3a9015acce076a1512b1615dc3b
patch
-
hackmd.io
/@haindpwn/cve-2026-121941-munt-midistreamparser-oversized-sysex-heap-overflow
exploit
-
github.com
/munt/munt/issues/149
issue-tracking
-
hackmd.io
/@haindpwn/munt-midistreamparser-oversized-sysex-heap-overflow
third-party-advisory
-
github.com
/munt/munt/blob/libmt32emu_2_8_3/mt32emu/src/MidiStreamParser.cpp#L223-L257
technical-description
-
vulncheck.com
/advisories/libmt32emu-before-2.8.4-heap-buffer-overflow-via-midistreamparserimpl-parsesysex
third-party-advisory
Sources
- CVE List CVE-2026-121941
- NVD CVE-2026-121941
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