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VulnerabilityPublished Updated

CVE-2026-72069: Linux kernel · locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in af28d801cd2db4cc7378554499bd4a5d84a5517e : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 53% 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 can 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 af28d801cd2db4cc7378554499bd4a5d84a5517e, 89038cc87d80c77e7aa6f42a64b2573b74af339f, 633cadbc0b8323f5cc140a285d2432089dbb534e +4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Aug 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
  • ≥ 0f383b6dc96e976dfbf2721b0bf10bd96103b341, < af28d801cd2db4cc7378554499bd4a5d84a5517e
Fixed in
  • af28d801cd2db4cc7378554499bd4a5d84a5517e
LinuxLinuxAffected
  • ≥ 0f383b6dc96e976dfbf2721b0bf10bd96103b341, < 89038cc87d80c77e7aa6f42a64b2573b74af339f
Fixed in
  • 89038cc87d80c77e7aa6f42a64b2573b74af339f
LinuxLinuxAffected
  • ≥ 0f383b6dc96e976dfbf2721b0bf10bd96103b341, < 633cadbc0b8323f5cc140a285d2432089dbb534e
Fixed in
  • 633cadbc0b8323f5cc140a285d2432089dbb534e
LinuxLinuxAffected
  • ≥ 0f383b6dc96e976dfbf2721b0bf10bd96103b341, < 83f9fb561c1c3917e19f95523dd933c7d30291aa
Fixed in
  • 83f9fb561c1c3917e19f95523dd933c7d30291aa
LinuxLinuxAffected
  • ≥ 0f383b6dc96e976dfbf2721b0bf10bd96103b341, < 9d1fcd64ab81200e02b7a6db5eb1da8e244e8289
Fixed in
  • 9d1fcd64ab81200e02b7a6db5eb1da8e244e8289
LinuxLinuxAffected
  • ≥ 0f383b6dc96e976dfbf2721b0bf10bd96103b341, < 3cfaac77b3c32ac3940df28866de263c3f45d24c
Fixed in
  • 3cfaac77b3c32ac3940df28866de263c3f45d24c

Description

In the Linux kernel, the following vulnerability has been resolved: locking/rt: Fix the incorrect RCU protection in rt_spin_unlock() rt_spin_unlock() releases the RCU protection before unlocking the lock. That opens the door for the following UAF scenario: T1 T2 spin_lock(&p->lock); rcu_read_lock(); invalidate(p); p = rcu_dereference(ptr); rcu_assign_pointer(ptr, NULL); if (!p) return; spin_unlock(&p->lock); spin_lock(&p->lock) lock(&lock->lock); rcu_read_lock(); kfree_rcu(p); rcu_read_unlock(); .... spin_unlock(&p->lock) rcu_read_unlock(); // Ends grace period rcu_do_batch() kfree(p); UAF -> rt_mutex_cmpxchg_release(&lock->lock...) Regular spinlocks keep preemption disabled accross the unlock operation, which provides full RCU protection, but the RT substitution fails to resemble that. Same applies for the rwlock substitution. Move the rcu_read_unlock() invocation past the unlock operations to match the non-RT semantics. This makes it asymmetric vs. rt_xxx_lock(), but that's harmless as the caller needs to hold RCU read lock across the lock operation. The migrate_enable() call stays before the unlock operation because there is no per CPU operation in the unlock path which would require migration to be kept disabled.

References

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