CVE-2025-21809

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-02-27. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

rxrpc, afs: Fix peer hash locking vs RCU callback

In its address list, afs now retains pointers to and refs on one or more rxrpc_peer objects. The address list is freed under RCU and at this time, it puts the refs on those peers.

Now, when an rxrpc_peer object runs out of refs, it gets removed from the peer hash table and, for that, rxrpc has to take a spinlock. However, it is now being called from afs's RCU cleanup, which takes place in BH context - but it is just taking an ordinary spinlock.

The put may also be called from non-BH context, and so there exists the possibility of deadlock if the BH-based RCU cleanup happens whilst the hash spinlock is held. This led to the attached lockdep complaint.

Fix this by changing spinlocks of rxnet->peer_hash_lock back to BH-disabling locks.

================================ WARNING: inconsistent lock state 6.13.0-rc5-build2+ #1223 Tainted: G E -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88810babe228 (&rxnet->peer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180 {SOFTIRQ-ON-W} state was registered at: mark_usage+0x164/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_peer_keepalive_worker+0x144/0x440 process_one_work+0x486/0x7c0 process_scheduled_works+0x73/0x90 worker_thread+0x1c8/0x2a0 kthread+0x19b/0x1b0 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30 irq event stamp: 972402 hardirqs last enabled at (972402): [] _raw_spin_unlock_irqrestore+0x2e/0x50 hardirqs last disabled at (972401): [] _raw_spin_lock_irqsave+0x18/0x60 softirqs last enabled at (972300): [] handle_softirqs+0x3ee/0x430 softirqs last disabled at (972313): [] __irq_exit_rcu+0x44/0x110

other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rxnet->peer_hash_lock); lock(&rxnet->peer_hash_lock);

* DEADLOCK * 1 lock held by swapper/1/0: #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30

stack backtrace: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G E 6.13.0-rc5-build2+ #1223 Tainted: [E]=UNSIGNED_MODULE Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Call Trace: dump_stack_lvl+0x57/0x80 print_usage_bug.part.0+0x227/0x240 valid_state+0x53/0x70 mark_lock_irq+0xa5/0x2f0 mark_lock+0xf7/0x170 mark_usage+0xe1/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_put_peer+0xcb/0x180 afs_free_addrlist+0x46/0x90 [kafs] rcu_do_batch+0x2d2/0x640 rcu_core+0x2f7/0x350 handle_softirqs+0x1ee/0x430 __irq_exit_rcu+0x44/0x110 irq_exit_rcu+0xa/0x30 sysvec_apic_timer_interrupt+0x7f/0xa0

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
25(Track)
EG Risk 25/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
4.5%
KEV
Not listed

Published

February 27, 2025

Last Modified

October 1, 2025

References (3)

Patch Availability(13)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-6.8 (6.8.0-64.67) @ noble2026-05-30ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1025.26) @ noble2026-05-30ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-64.67~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-26.26) @ oracular2026-05-30ubuntu
ubuntulinux-tools-aws (6.11.0-1014.15) @ oracular2026-05-30ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1029.30) @ noble2026-05-30ubuntu
ubuntulinux-tools-oracle-64k (6.11.0-1016.17) @ oracular2026-05-30ubuntu
ubuntulinux-tools-lowlatency-hwe-20.04-edge (6.8.0-64.67.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-gcp-lts-24.04 (6.8.0-1033.35) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2026.27) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-6.8 (6.8.0-1031.35) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-nvidia-lts-24.04 (6.8.0-1022.23) @ noble2026-05-30ubuntu
linuxKernel @ 6.12.13—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(12)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 11× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-24 14:17 UTCEPSS rescore
  2. 2026-07-24 13:41 UTCOSV refresh
  3. 2026-07-23 14:17 UTCEPSS rescore
  4. 2026-07-23 02:50 UTCEG score recompute
  5. 2026-07-22 14:07 UTCEPSS rescore
  6. 2026-07-22 14:07 UTCEPSS rescore
  7. 2026-07-21 15:24 UTCEPSS rescore
  8. 2026-07-20 17:07 UTCEPSS rescore
  9. 2026-07-19 14:30 UTCEPSS rescore
  10. 2026-07-19 14:30 UTCEPSS rescore
  11. 2026-07-18 10:03 UTCEPSS rescore
  12. 2026-07-16 17:02 UTCEPSS rescore
  13. 2026-07-15 16:57 UTCEPSS rescore
  14. 2026-07-15 16:57 UTCEPSS rescore
  15. 2026-07-15 01:59 UTCEPSS rescore
  16. 2026-07-13 22:29 UTCEPSS rescore
  17. 2026-07-13 22:29 UTCEPSS rescore
  18. 2026-07-13 06:12 UTCEPSS rescore
  19. 2026-07-13 06:12 UTCEPSS rescore
  20. 2026-07-12 05:46 UTCEPSS rescore
  21. 2026-07-12 05:46 UTCEPSS rescore
  22. 2026-07-11 08:27 UTCEPSS rescore
  23. 2026-07-11 08:26 UTCEPSS rescore
  24. 2026-07-09 19:09 UTCEPSS rescore
  25. 2026-07-08 15:14 UTCEPSS rescore
Show 66 more
  1. 2026-07-07 13:45 UTCEPSS rescore
  2. 2026-07-07 08:51 UTCOSV refresh
  3. 2026-07-06 02:22 UTCEPSS rescore
  4. 2026-07-06 02:22 UTCEPSS rescore
  5. 2026-07-05 02:30 UTCEPSS rescore
  6. 2026-07-04 06:30 UTCEPSS rescore
  7. 2026-07-01 15:06 UTCEPSS rescore
  8. 2026-06-30 23:21 UTCEPSS rescore
  9. 2026-06-30 23:21 UTCEPSS rescore
  10. 2026-06-29 14:06 UTCEPSS rescore
  11. 2026-06-28 14:07 UTCEPSS rescore
  12. 2026-06-28 14:07 UTCEPSS rescore
  13. 2026-06-28 04:55 UTCEPSS rescore
  14. 2026-06-28 04:55 UTCEPSS rescore
  15. 2026-06-27 03:08 UTCEPSS rescore
  16. 2026-06-27 03:08 UTCEPSS rescore
  17. 2026-06-25 13:49 UTCEPSS rescore
  18. 2026-06-25 13:49 UTCEPSS rescore
  19. 2026-06-24 14:04 UTCEPSS rescore
  20. 2026-06-24 14:04 UTCEPSS rescore
  21. 2026-06-23 21:32 UTCEPSS rescore
  22. 2026-06-23 21:32 UTCEPSS rescore
  23. 2026-06-22 14:25 UTCEPSS rescore
  24. 2026-06-22 14:25 UTCEPSS rescore
  25. 2026-06-21 01:59 UTCEPSS rescore
  26. 2026-06-21 01:59 UTCEPSS rescore
  27. 2026-06-19 19:25 UTCEPSS rescore
  28. 2026-06-19 19:25 UTCEPSS rescore
  29. 2026-06-18 20:05 UTCOSV refresh
  30. 2026-06-18 17:52 UTCEPSS rescore
  31. 2026-06-18 17:52 UTCEPSS rescore
  32. 2026-06-17 17:52 UTCEPSS rescore
  33. 2026-06-16 17:52 UTCEPSS rescore
  34. 2026-06-16 17:52 UTCEPSS rescore
  35. 2026-06-15 17:48 UTCEPSS rescore
  36. 2026-06-14 23:17 UTCEPSS rescore
  37. 2026-06-13 22:59 UTCEPSS rescore
  38. 2026-06-12 23:11 UTCEPSS rescore
  39. 2026-06-11 13:59 UTCEPSS rescore
  40. 2026-06-10 22:18 UTCEPSS rescore
  41. 2026-06-10 13:22 UTCEPSS rescore
  42. 2026-06-08 14:16 UTCEPSS rescore
  43. 2026-06-08 14:16 UTCEPSS rescore
  44. 2026-06-07 15:24 UTCEPSS rescore
  45. 2026-06-07 15:24 UTCEPSS rescore
  46. 2026-06-06 13:47 UTCEPSS rescore
  47. 2026-06-06 13:47 UTCEPSS rescore
  48. 2026-06-05 22:46 UTCEPSS rescore
  49. 2026-06-05 22:46 UTCEPSS rescore
  50. 2026-06-05 06:10 UTCEPSS rescore
  51. 2026-06-05 06:10 UTCEPSS rescore
  52. 2026-06-04 13:11 UTCEPSS rescore
  53. 2026-06-04 13:11 UTCEPSS rescore
  54. 2026-06-02 20:12 UTCEPSS rescore
  55. 2026-06-02 20:12 UTCEPSS rescore
  56. 2026-06-01 13:51 UTCEPSS rescore
  57. 2026-06-01 13:51 UTCEPSS rescore
  58. 2026-05-31 22:30 UTCEPSS rescore
  59. 2026-05-31 22:30 UTCEPSS rescore
  60. 2026-05-31 00:16 UTCEPSS rescore
  61. 2026-05-31 00:16 UTCEPSS rescore
  62. 2026-05-30 10:28 UTCEG score recompute
  63. 2026-05-30 10:28 UTCVendor advisory
  64. 2026-05-30 10:28 UTCGHSA enrichment
  65. 2026-05-29 16:50 UTCOSV refresh
  66. 2026-05-29 13:44 UTCEPSS rescore

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-21809?
CVE-2025-21809 is a medium vulnerability published on February 27, 2025. In the Linux kernel, the following vulnerability has been resolved: rxrpc, afs: Fix peer hash locking vs RCU callback In its address list, afs now retains pointers to and refs on one or more rxrpc_peer objects. The address list is freed under RCU and at this time, it puts the refs on those peers.…
When was CVE-2025-21809 disclosed?
CVE-2025-21809 was first published in the National Vulnerability Database on February 27, 2025, with the most recent update on October 1, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21809 actively exploited?
CVE-2025-21809 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-21809?
CVE-2025-21809 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21809?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21809, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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