CVE-2025-39909 mm/damon/lru_sort: avoid divide-by-zero in damon_lru_sort_apply_parameters()
A divide-by-zero error in the Linux kernel's DAMON LRU_SORT module can cause a system crash if specific parameters are misconfigured.
- 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-2025-39909?
CVE-2025-39909 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 1 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:
mm/damon/lru_sort: avoid divide-by-zero in damon_lru_sort_apply_parameters()
Patch series "mm/damon: avoid divide-by-zero in DAMON module's parameters application".
DAMON's RECLAIM and LRU_SORT modules perform no validation on user-configured parameters during application, which may lead to division-by-zero errors.
Avoid the divide-by-zero by adding validation checks when DAMON modules attempt to apply the parameters.
This patch (of 2):
During the calculation of 'hot_thres' and 'cold_thres', either 'sample_interval' or 'aggr_interval' is used as the divisor, which may lead to division-by-zero errors. Fix it by directly returning -EINVAL when such a case occurs. Additionally, since 'aggr_interval' is already required to be set no smaller than 'sample_interval' in damon_set_attrs(), only the case where 'sample_interval' is zero needs to be checked.
Weakness: CWE-369
Which versions are affected by CVE-2025-39909?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-39909?
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-2025-39909 being exploited?
There is no known exploitation of CVE-2025-39909 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-68013, BELL-CVE-2025-39909, DEBIAN-CVE-2025-39909, GHSA-jh5r-m3qc-3584, ROOT-OS-UBUNTU-2404-CVE-2025-39909, UBUNTU-CVE-2025-39909.