CVE-2025-39954 clk: sunxi-ng: mp: Fix dual-divider clock rate readback
A missing divider offset in the Linux kernel clock driver causes divide-by-zero errors, potentially leading to system crashes or denial of service.
- 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-2025-39954?
CVE-2025-39954 is a medium-severity denial of service vulnerability in Linux kernel, published on 9 Oct 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:
clk: sunxi-ng: mp: Fix dual-divider clock rate readback
When dual-divider clock support was introduced, the P divider offset was left out of the .recalc_rate readback function. This causes the clock rate to become bogus or even zero (possibly due to the P divider being 1, leading to a divide-by-zero).
Fix this by incorporating the P divider offset into the calculation.
Weakness: CWE-369
Which versions are affected by CVE-2025-39954?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-39954?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-39954 being exploited?
There is no known exploitation of CVE-2025-39954 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-39954, DEBIAN-CVE-2025-39954, GHSA-g295-3qg8-vf4w, UBUNTU-CVE-2025-39954.