CVE-2025-39694 s390/sclp: Fix SCCB present check
A logic error in the Linux kernel s390 SCLP handler fails to detect NULL pointers before address translation, potentially causing incorrect memory access and system crashes.
- 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-2025-39694?
CVE-2025-39694 is a high-severity vulnerability in Debian Debian Linux, published on 5 Sep 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:
s390/sclp: Fix SCCB present check
Tracing code called by the SCLP interrupt handler contains early exits if the SCCB address associated with an interrupt is NULL. This check is performed after physical to virtual address translation.
If the kernel identity mapping does not start at address zero, the resulting virtual address is never zero, so that the NULL checks won't work. Subsequently this may result in incorrect accesses to the first page of the identity mapping.
Fix this by introducing a function that handles the NULL case before address translation.
Weakness: CWE-476
Which versions are affected by CVE-2025-39694?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39694?
Apply the vendor's patch.
Is CVE-2025-39694 being exploited?
There is no known exploitation of CVE-2025-39694 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-39694, DEBIAN-CVE-2025-39694, GHSA-wxfj-mrv6-qf72, ROOT-OS-DEBIAN-12-CVE-2025-39694, ROOT-OS-DEBIAN-13-CVE-2025-39694, ROOT-OS-UBUNTU-2404-CVE-2025-39694 and 1 more.