CVE-2025-21671 zram: fix potential UAF of zram table
A use-after-free vulnerability in the Linux kernel zram driver allows attackers to potentially execute code or escalate privileges via a failed device reset.
- 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-2025-21671?
CVE-2025-21671 is a high-severity use after free vulnerability in Linux kernel, published on 31 Jan 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:
zram: fix potential UAF of zram table
If zram_meta_alloc failed early, it frees allocated zram->table without setting it NULL. Which will potentially cause zram_meta_free to access the table if user reset an failed and uninitialized device.
Weakness: CWE-416
Which versions are affected by CVE-2025-21671?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21671?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-21671 being exploited?
There is no known exploitation of CVE-2025-21671 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-21671, DEBIAN-CVE-2025-21671, GHSA-7792-f3h4-qxjq, UBUNTU-CVE-2025-21671.