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Vulnerabilities

Vulnerability · CVE-2026-23342

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix race in cpumap on PREEMPT_RT On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be…

Published Mar 25, 2026 · catalog updated Jun 17, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2026-23342. EPSS is 0.09%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium4.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.09%
Remediation
Advisory link
Affected products
cpe linux/linux kernel

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix race in cpumap on PREEMPT_RT On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed concurrently by multiple preemptible tasks on the same CPU. The original code assumes bq_enqueue() and __cpu_map_flush() run atomically with respect to each other on the same CPU, relying on local_bh_disable() to prevent preemption. However, on PREEMPT_RT, local_bh_disable() only calls migrate_disable() (when PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable preemption, which allows CFS scheduling to preempt a task during bq_flush_to_queue(), enabling another task on the same CPU to enter bq_enqueue() and operate on the same per-CPU bq concurrently. This leads to several races: 1. Double __list_del_clearprev(): after bq->count is reset in bq_flush_to_queue(), a preempting task can call bq_enqueue() -> bq_flush_to_queue() on the same bq when bq->count reaches CPU_MAP_BULK_SIZE. Both tasks then call __list_del_clearprev() on the same bq->flush_node, the second call dereferences the prev pointer that was already set to NULL by the first. 2. bq->count and bq->q[] races: concurrent bq_enqueue() can corrupt the packet queue while bq_flush_to_queue() is processing it. The race between task A (__cpu_map_flush -> bq_flush_to_queue) and task B (bq_enqueue -> bq_flush_to_queue) on the same CPU: Task A (xdp_do_flush) Task B (cpu_map_enqueue) ---------------------- ------------------------ bq_flush_to_queue(bq) spin_lock(&q->producer_lock) /* flush bq->q[] to ptr_ring */ bq->count = 0 spin_unlock(&q->producer_lock) bq_enqueue(rcpu, xdpf) bq->q[bq->count++] = xdpf /* ... more enqueues until full ... */ bq_flush_to_queue(bq) spin_lock(&q->producer_lock) /* flush to ptr_ring */ spin_unlock(&q->producer_lock) __list_del_clearprev(flush_node) /* sets flush_node.prev = NULL */ __list_del_clearprev(flush_node) flush_node.prev->next = ... /* prev is NULL -> kernel oops */ Fix this by adding a local_lock_t

Are you affected?

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  • cpe linux/linux kernel6.18
  • cpe linux/linux kernel7.0

How to fix CVE-2026-23342

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-23342. EPSS is 0.09%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with linux/linux kernel 6.18; linux/linux kernel 7.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-362: Race Condition. EPSS 0.09%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 25, 2026 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: bpf: Fix race in cpumap on PREEMPT_RT On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed concurrently by multiple preemptible tasks on the same CPU. The original code assumes bq_enqueue() and __cpu_map_flush() run atomically with respect to each other on the same CPU, relying on local_bh_disable() to prevent pr

  2. Jun 17, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: bpf: Fix race in cpumap on PREEMPT_RT On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed concurrently by multiple preemptible tasks on the same CPU. The original code assumes bq_enqueue() and __cpu_map_flush() run atomically with respect to each other on the same CPU, relying on local_bh_disable() to prevent pr

Sources

  • CVE.orgVulnerability recordCVE-2026-23342

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-23342

    30-day exploitation probability 0.1%

    first.org
  • NIST NVDVulnerability recordCVE-2026-23342

    In the Linux kernel, the following vulnerability has been resolved: bpf: Fix race in cpumap on PREEMPT_RT On PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed concurrently by multiple preemptible tasks on the same CPU. The original code assumes bq_enqueue() a

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.