irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 5.16 and later | 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11, 7.1 | Patch available | CNA |
- Linux VendorLinux Affected 5.16 and later Fixed in 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11, 7.1 Patch available CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.16 to before 6.1.175; 6.2 to before 6.6.142; 6.7 to before 6.12.92; 6.13 to before 6.18.34; 6.19 to before 7.0.11 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* | 7.1 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* | 7.1 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* | 7.1 rc3 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.16 to before 6.1.175; 6.2 to before 6.6.142; 6.7 to before 6.12.92; 6.13 to before 6.18.34; 6.19 to before 7.0.11 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* Versions 7.1 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* Versions 7.1 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* Versions 7.1 rc3 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.175, 6.6.142, 6.12.92, 6.18.34, 7.0.11, 7.1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2026-64073
- 2026-10-03 Alias added: GHSA-8ffv-2j52-h7h3
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-19 Weakness changed · CISA ADP
- 2026-10-27 CVSS score changed · Red Hat
References
Patch 6
- https://git.kernel.org/stable/c/2dc79362302922cb18f35e262712b5e58de65442
- https://git.kernel.org/stable/c/eef4f71b46a9929ac33e968538c9dd5d96a02460
- https://git.kernel.org/stable/c/684a78183c54c23e70d1cba320f7fc184604210b
- https://git.kernel.org/stable/c/18c0456ea2615b1a743a6db739c74411c3b42bc6
- https://git.kernel.org/stable/c/81b582784518196eff1050212a046bc29d3a05dd
- https://git.kernel.org/stable/c/91840be8f710370607f949a627e070896faeddb8
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Sources
- CVE-2026-64073 · CVE Program
- CVE-2026-64073 · NVD
- FIRST EPSS
- GHSA-8ffv-2j52-h7h3 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-64073 · Red Hat security data · CC BY 4.0
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