CVE-2026-72103 dm: avoid leaking the caller's thread keyring via the table device file
An attacker with CAP_SYS_ADMIN can recover LUKS volume keys from RAM after suspend due to a kernel bug leaking the keyring reference.
- 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-2026-72103?
CVE-2026-72103 is a high-severity vulnerability in Linux, published on 15 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:
dm: avoid leaking the caller's thread keyring via the table device file
The refactoring in commit a28d893eb327 ("md: port block device access to file") accidentally causes the caller's thread keyring to be kept alive long beyond the caller's lifetime.
As a result, "cryptsetup luksSuspend" silently fails to wipe the LUKS volume key from memory.
In detail: "cryptsetup luksOpen" uses its supposedly ephemeral thread keyring to pass the volume key to the kernel. dm-crypt's crypt_set_keyring_key() copies the key material into its own crypt_config structure and then drops its own reference to the key in the keyring with key_put().
With this fix, restoring pre-v6.9 behavior, the copy in the thread keyring is then promptly garbage collected, such that exactly one copy of the volume key remains. This single copy is correctly wiped from memory on "cryptsetup luksSuspend".
Without this fix, the thread keyring and the volume key in it remains. This second copy is only freed on "luksClose". "luksSuspend" neither knows about this copy nor has any way to remove it, so the key remains recoverable from RAM after a suspend that is documented to have wiped it.
This fix should not introduce new security problems, as the code is anyway gated by CAP_SYS_ADMIN. The device-mapper core, not the calling task, is the legitimate owner of this long-lived file.
Weakness: CWE-200
Which versions are affected by CVE-2026-72103?
How do I fix CVE-2026-72103?
Apply the vendor's patch.
Is CVE-2026-72103 being exploited?
There is no known exploitation of CVE-2026-72103 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72103, DEBIAN-CVE-2026-72103, GHSA-mq86-3x2m-mwpc, UBUNTU-CVE-2026-72103.