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VulnerabilityPublished Updated

CVE-2026-64073: Linux kernel · irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in eef4f71b46a9929ac33e968538c9dd5d96a02460 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in eef4f71b46a9929ac33e968538c9dd5d96a02460, 91840be8f710370607f949a627e070896faeddb8, 684a78183c54c23e70d1cba320f7fc184604210b +3
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 810979682ccc98dbd83f341c18a2e556c30a7164, < eef4f71b46a9929ac33e968538c9dd5d96a02460
Fixed in
  • eef4f71b46a9929ac33e968538c9dd5d96a02460
LinuxLinuxAffected
  • ≥ 810979682ccc98dbd83f341c18a2e556c30a7164, < 91840be8f710370607f949a627e070896faeddb8
Fixed in
  • 91840be8f710370607f949a627e070896faeddb8
LinuxLinuxAffected
  • ≥ 810979682ccc98dbd83f341c18a2e556c30a7164, < 684a78183c54c23e70d1cba320f7fc184604210b
Fixed in
  • 684a78183c54c23e70d1cba320f7fc184604210b
LinuxLinuxAffected
  • ≥ 810979682ccc98dbd83f341c18a2e556c30a7164, < 81b582784518196eff1050212a046bc29d3a05dd
Fixed in
  • 81b582784518196eff1050212a046bc29d3a05dd
LinuxLinuxAffected
  • ≥ 810979682ccc98dbd83f341c18a2e556c30a7164, < 18c0456ea2615b1a743a6db739c74411c3b42bc6
Fixed in
  • 18c0456ea2615b1a743a6db739c74411c3b42bc6
LinuxLinuxAffected
  • ≥ 810979682ccc98dbd83f341c18a2e556c30a7164, < 2dc79362302922cb18f35e262712b5e58de65442
Fixed in
  • 2dc79362302922cb18f35e262712b5e58de65442

Description

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 this by wrapping run_irq_workd() in guard(rcu)() so that the entire irq_work_single() execution is within an RCU read-side critical section. Then add synchronize_rcu() in irq_work_sync() after rcuwait_wait_event() to ensure the caller waits for the RCU grace period before returning, preventing premature frees.

References

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