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EUVD-2026-317153

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-02 07:38

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

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{
  "assigner": "ENISA",
  "date_reserved": "2026-10-02T07:38:21.777744+00:00",
  "id": "EUVD-2026-317153"
}

CVE-2025-39749 (GCVE-0-2025-39749)

Vulnerability from cvelistv5 – Published: 2025-09-11 16:52 – Updated: 2026-05-12 12:06

Title

rcu: Protect ->defer_qs_iw_pending from data race

Summary

In the Linux kernel, the following vulnerability has been resolved: rcu: Protect ->defer_qs_iw_pending from data race On kernels built with CONFIG_IRQ_WORK=y, when rcu_read_unlock() is invoked within an interrupts-disabled region of code [1], it will invoke rcu_read_unlock_special(), which uses an irq-work handler to force the system to notice when the RCU read-side critical section actually ends. That end won't happen until interrupts are enabled at the soonest. In some kernels, such as those booted with rcutree.use_softirq=y, the irq-work handler is used unconditionally. The per-CPU rcu_data structure's ->defer_qs_iw_pending field is updated by the irq-work handler and is both read and updated by rcu_read_unlock_special(). This resulted in the following KCSAN splat: ------------------------------------------------------------------------ BUG: KCSAN: data-race in rcu_preempt_deferred_qs_handler / rcu_read_unlock_special read to 0xffff96b95f42d8d8 of 1 bytes by task 90 on cpu 8: rcu_read_unlock_special+0x175/0x260 __rcu_read_unlock+0x92/0xa0 rt_spin_unlock+0x9b/0xc0 __local_bh_enable+0x10d/0x170 __local_bh_enable_ip+0xfb/0x150 rcu_do_batch+0x595/0xc40 rcu_cpu_kthread+0x4e9/0x830 smpboot_thread_fn+0x24d/0x3b0 kthread+0x3bd/0x410 ret_from_fork+0x35/0x40 ret_from_fork_asm+0x1a/0x30 write to 0xffff96b95f42d8d8 of 1 bytes by task 88 on cpu 8: rcu_preempt_deferred_qs_handler+0x1e/0x30 irq_work_single+0xaf/0x160 run_irq_workd+0x91/0xc0 smpboot_thread_fn+0x24d/0x3b0 kthread+0x3bd/0x410 ret_from_fork+0x35/0x40 ret_from_fork_asm+0x1a/0x30 no locks held by irq_work/8/88. irq event stamp: 200272 hardirqs last enabled at (200272): [<ffffffffb0f56121>] finish_task_switch+0x131/0x320 hardirqs last disabled at (200271): [<ffffffffb25c7859>] __schedule+0x129/0xd70 softirqs last enabled at (0): [<ffffffffb0ee093f>] copy_process+0x4df/0x1cc0 softirqs last disabled at (0): [<0000000000000000>] 0x0 ------------------------------------------------------------------------ The problem is that irq-work handlers run with interrupts enabled, which means that rcu_preempt_deferred_qs_handler() could be interrupted, and that interrupt handler might contain an RCU read-side critical section, which might invoke rcu_read_unlock_special(). In the strict KCSAN mode of operation used by RCU, this constitutes a data race on the ->defer_qs_iw_pending field. This commit therefore disables interrupts across the portion of the rcu_preempt_deferred_qs_handler() that updates the ->defer_qs_iw_pending field. This suffices because this handler is not a fast path.

Severity

No CVSS data available.

Assigner

Linux mitre root Scorecard

References

12 references

URL	Tags
https://git.kernel.org/stable/c/74f58f382a7c8333f…
https://git.kernel.org/stable/c/f937759c7432d6151…
https://git.kernel.org/stable/c/0ad84d62217488e67…
https://git.kernel.org/stable/c/b5de8d80b5d049f05…
https://git.kernel.org/stable/c/b55947b725f190396…
https://git.kernel.org/stable/c/e35e711c78c8a4c43…
https://git.kernel.org/stable/c/90de9c94ea72327cf…
https://git.kernel.org/stable/c/55e11f6776798b27c…
https://git.kernel.org/stable/c/90c09d57caeca94e6…
https://lists.debian.org/debian-lts-announce/2025…
https://lists.debian.org/debian-lts-announce/2025…
https://cert-portal.siemens.com/productcert/html/…

Impacted products

3 products

Vendor	Product	Version
Linux	Linux	Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 74f58f382a7c8333f8d09701aefaa25913bdbe0e (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < f937759c7432d6151b73e1393b6517661813d506 (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 0ad84d62217488e679ecc90e8628980dcc003de3 (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < b5de8d80b5d049f051b95d9b1ee50ae4ab656124 (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < b55947b725f190396f475d5d0c59aa855a4d8895 (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < e35e711c78c8a4c43330c0dcb1c4d507a19c20f4 (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 90de9c94ea72327cfa9c2c9f6113c23a513af60b (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 55e11f6776798b27cf09a7aa0d718415d4fc9cf5 (git) Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 90c09d57caeca94e6f3f87c49e96a91edd40cbfd (git)
Linux	Linux	Affected: 5.3 Unaffected: 0 , < 5.3 (semver) Unaffected: 5.4.297 , ≤ 5.4.* (semver) Unaffected: 5.10.241 , ≤ 5.10.* (semver) Unaffected: 5.15.190 , ≤ 5.15.* (semver) Unaffected: 6.1.149 , ≤ 6.1.* (semver) Unaffected: 6.6.103 , ≤ 6.6.* (semver) Unaffected: 6.12.43 , ≤ 6.12.* (semver) Unaffected: 6.15.11 , ≤ 6.15.* (semver) Unaffected: 6.16.2 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix)
Siemens	SIMATIC CN 4100	Affected: 0 , < V5.0 (custom)

Show details on NVD website

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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EUVD-2026-317153

CVE-2025-39749 (GCVE-0-2025-39749)

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