CVE-2025-39715 parisc: Revise gateway LWS calls to probe user read access
A flaw in the Linux kernel allows user code to bypass read protection checks during LWS compare and swap operations on PA-RISC architecture.
- 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-2025-39715?
CVE-2025-39715 is a medium-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:
parisc: Revise gateway LWS calls to probe user read access
We use load and stbys,e instructions to trigger memory reference interruptions without writing to memory. Because of the way read access support is implemented, read access interruptions are only triggered at privilege levels 2 and 3. The kernel and gateway page execute at privilege level 0, so this code never triggers a read access interruption. Thus, it is currently possible for user code to execute a LWS compare and swap operation at an address that is read protected at privilege level 3 (PRIV_USER).
Fix this by probing read access rights at privilege level 3 and branching to lws_fault if access isn't allowed.
Which versions are affected by CVE-2025-39715?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39715?
Apply the vendor's patch.
Is CVE-2025-39715 being exploited?
There is no known exploitation of CVE-2025-39715 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-67004, BELL-CVE-2025-39715, DEBIAN-CVE-2025-39715, GHSA-whrv-v478-pw4q, ROOT-OS-DEBIAN-11-CVE-2025-39715, ROOT-OS-DEBIAN-12-CVE-2025-39715 and 4 more.