CVE-2025-37891 ALSA: ump: Fix buffer overflow at UMP SysEx message conversion
A buffer overflow in the Linux kernel ALSA UMP driver allows attackers to corrupt memory and potentially execute code via crafted SysEx messages.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-37891?
CVE-2025-37891 is a high-severity memory corruption vulnerability in Linux kernel, published on 19 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-120
Which versions are affected by CVE-2025-37891?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-37891?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-37891 being exploited?
There is no known exploitation of CVE-2025-37891 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-37891, DEBIAN-CVE-2025-37891, GHSA-6875-67c4-4637, ROOT-OS-UBUNTU-2404-CVE-2025-37891, UBUNTU-CVE-2025-37891.