CVE-2026-90333 Linux CVE debrief

Who should care

Linux administrators and users of dm-integrity, particularly those with raw write access to backing devices, should assess exposure and apply patches. They should also verify the integrity of dm-integrity configurations and monitor for suspicious discard block activity to detect potential attacks.

Why it matters

CVE-2026-90333 allows an attacker with raw write access to the backing device to forge discard blocks, bypassing HMAC verification in the Linux kernel's dm-integrity feature. Linux administrators and users of dm-integrity should assess exposure and apply patches.

• Verify integrity of dm-integrity configurations to prevent data tampering
• Monitor for suspicious discard block activity to detect potential attacks
• Apply patches for Linux kernel versions 5.7 and earlier to prevent exploitation

Technical summary

The Linux kernel's dm-integrity feature uses a forgeable discard filler, allowing an attacker with raw write access to the backing device to stamp any block with an all-0xf6 tag, bypassing HMAC verification. The vulnerability is resolved by replacing the forgeable discard filler with a keyed sector marker, computed by integrity_discard_checksum(). This change ensures that discarded blocks are marked with a unique checksum based on a salt and the sector number, preventing an attacker from forging discard blocks without knowledge of the integrity key.

Defensive priority

Assess exposure and apply patches for Linux kernel versions 5.7 and earlier. Verify integrity of dm-integrity configurations and monitor for suspicious discard block activity.

Recommended defensive actions

• Assess exposure and apply patches for Linux kernel versions 5.7 and earlier
• Verify integrity of dm-integrity configurations
• Monitor for suspicious discard block activity
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance

Evidence notes

The CVE record and source item provide details on the vulnerability and its resolution. Linux kernel versions 5.7 and earlier are affected. The NVD entry is currently not provided. To verify the integrity of dm-integrity configurations and detect potential attacks, defenders should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also check relevant monitoring, detection, and logs for exposed assets that need extra review.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.