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Review reviewHigh

CVE-2026-64073

Linux

In the Linux kernel, the following vulnerability has been resolved: irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via run_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0. After irq_work_single() clears BUSY via atomic_cmpxchg(), it still dereferences @work for irq_work_is_hard() and rcuwait_wake_up(). An irq_work_sync() caller on another CPU that enters after BUSY is cleared can observe BUSY==0 immediately, return, and free the work before those accesses complete — causing a use-after-free. Fix th...

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via run_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0. After irq_work_single() clears BUSY via atomic_cmpxchg(), it still dereferences @work for irq_work_is_hard() and rcuwait_wake_up(). An irq_work_sync() caller on another CPU that enters after BUSY is cleared can observe BUSY==0 immediately, return, and free the work before those accesses complete — causing a use-after-free. Fix th...

Affected product and versions

Product
Linux
Affected versions
>= 810979682ccc98dbd83f341c18a2e556c30a7164 < 2dc79362302922cb18f35e262712b5e58de65442, >= 810979682ccc98dbd83f341c18a2e556c30a7164 < eef4f71b46a9929ac33e968538c9dd5d96a02460, >= 810979682ccc98dbd83f341c18a2e556c30a7164 < 684a78183c54c23e70d1cba320f7fc184604210b, >= 810979682ccc98dbd83f341c18a2e556c30a7164 < 18c0456ea2615b1a743a6db739c74411c3b42bc6, >= 810979682ccc98dbd83f341c18a2e556c30a7164 < 81b582784518196eff1050212a046bc29d3a05dd, >= 810979682ccc98dbd83f341c18a2e556c30a7164 < 91840be8f710370607f949a627e070896faeddb8, >= 5.16
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
Not available
CVE-2026-64073 — Linux | SECUFOCUS NOW