CVE-2026-90333 dm-integrity: replace forgeable discard filler with a keyed sector marker
An attacker with raw write access can bypass integrity checks by forging discard markers, requiring local access and specific configuration.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90333?
CVE-2026-90333 is a vulnerability in Linux, published on 17 Sep 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-integrity: replace forgeable discard filler with a keyed sector marker
The discard-block check in dm_integrity_rw_tag() treats a stored tag of all 0xf6 bytes (DISCARD_FILLER) as proof a block was discarded and skips HMAC verification. allow_discards is only accepted in dm-integrity's standalone mode. An attacker with raw write access to the backing device, but without the integrity key, can stamp any block with an all-0xf6 tag and have it served as authentic.
Add a new "allow_discards_keyed" target argument that marks discarded blocks with a keyed checksum of (salt || sector) instead, computed by integrity_discard_checksum().
Which versions are affected by CVE-2026-90333?
How do I fix CVE-2026-90333?
Apply the vendor's patch.
Is CVE-2026-90333 being exploited?
There is no known exploitation of CVE-2026-90333 in the wild and no public exploit code.
Sources
Also known as AZL-102681, BELL-CVE-2026-90333, DEBIAN-CVE-2026-90333, GHSA-62c9-4g59-6rj6, UBUNTU-CVE-2026-90333.