CVE-2026-68147 fscrypt: Avoid dynamic allocation in fscrypt_get_devices()
A use-after-free vulnerability in the Linux kernel's fscrypt module allows attackers to potentially execute code or cause a denial of service via dynamic allocation failures.
- 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-2026-68147?
CVE-2026-68147 is a high-severity use after free vulnerability in Linux, published on 10 Aug 2026. 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:
fscrypt: Avoid dynamic allocation in fscrypt_get_devices()
When a blk_crypto_key starts being used or is evicted, fs/crypto/ calls fscrypt_get_devices() to get the filesystem's list of block devices, then iterates over them and calls blk_crypto_config_supported(), blk_crypto_start_using_key(), or blk_crypto_evict_key() on each one.
Currently, the block device pointers are placed in a dynamically allocated array. This dynamic allocation is problematic because:
- It can fail, especially at the fscrypt_destroy_inline_crypt_key() call site when it's invoked for inode eviction under direct reclaim.
- fscrypt_destroy_inline_crypt_key() doesn't handle the failure. It just zeroizes and frees the blk_crypto_key without calling blk_crypto_evict_key(). That causes a use-after-free.
For now, let's fix this in the straightforward and easily-backportable way by switching to an on-stack array. Currently the fscrypt multi-device functionality is used only by f2fs, which has a hardcoded limit of 8 block devices. An on-stack array works fine for that.
(Of course, this solution won't scale up to large number of block devices. For that we'd need a different solution, like moving the block device iteration into the filesystem. Or in the case of btrfs, which will only support blk-crypto-fallback, we should make it just call blk-crypto-fallback directly, so the block devices won't be needed.)
Which versions are affected by CVE-2026-68147?
How do I fix CVE-2026-68147?
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-2026-68147 being exploited?
There is no known exploitation of CVE-2026-68147 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-68147, DEBIAN-CVE-2026-68147, GHSA-m9pv-2424-h7vv, UBUNTU-CVE-2026-68147.