CVE-2025-38579 f2fs: fix KMSAN uninit-value in extent_info usage
A local attacker can read uninitialized kernel memory via the f2fs filesystem, potentially exposing sensitive data.
- 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-2025-38579?
CVE-2025-38579 is a high-severity vulnerability in Debian Debian Linux, published on 19 Aug 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:
f2fs: fix KMSAN uninit-value in extent_info usage
KMSAN reported a use of uninitialized value in `__is_extent_mergeable()` and `__is_back_mergeable()` via the read extent tree path.
The root cause is that `get_read_extent_info()` only initializes three fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the remaining fields uninitialized. This leads to undefined behavior when those fields are accessed later, especially during extent merging.
Fix it by zero-initializing the `extent_info` struct before population.
Weakness: CWE-908
Which versions are affected by CVE-2025-38579?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38579?
Apply the vendor's patch.
Is CVE-2025-38579 being exploited?
There is no known exploitation of CVE-2025-38579 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-38579, DEBIAN-CVE-2025-38579, GHSA-6x6v-877j-v9fv, ROOT-OS-DEBIAN-12-CVE-2025-38579, ROOT-OS-DEBIAN-13-CVE-2025-38579, ROOT-OS-UBUNTU-2204-CVE-2025-38579 and 2 more.