CVE-2026-97931 ALSA: us122l: Prevent write upgrades for read mappings
A local attacker with access to the hwdep node can escalate privileges or execute code by exploiting a memory mapping permission flaw in the ALSA us122l driver.
- 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-2026-97931?
CVE-2026-97931 is a high-severity vulnerability in Linux, published on 25 Sep 2026. 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: us122l: Prevent write upgrades for read mappings
The hwdep mmap callback rejects read-buffer mappings that are initially writable, but leaves VM_MAYWRITE set on mappings created with PROT_READ. A process that can open the hwdep node O_RDWR can later use mprotect() to make the mapping writable.
The read allocation begins with struct usb_stream. Its read_size member is used by the fault handler to decide which pages belong to the read buffer. The read VMA intentionally remains expandable because pcm_usb_stream uses mremap() after reading that size. Changing read_size first can therefore map and access pages beyond the allocation. The same member is also consumed by usb_stream_free(), where changing it can make free_pages_exact() release pages outside the allocation.
Clear VM_MAYWRITE for read-buffer mappings after rejecting an initially writable VMA. This keeps the separate output-buffer mapping writable while preventing later permission upgrades.
Which versions are affected by CVE-2026-97931?
How do I fix CVE-2026-97931?
Apply the vendor's patch.
Is CVE-2026-97931 being exploited?
There is no known exploitation of CVE-2026-97931 in the wild and no public exploit code.
Sources
Also known as AZL-104823, BELL-CVE-2026-97931, DEBIAN-CVE-2026-97931, GHSA-vp4m-4hj6-cc9p, UBUNTU-CVE-2026-97931.