CVE-2025-21655

MEDIUMNVD 4.74.7—
EchelonGraph scoreMEDIUM confidence

Score 4.7 from GitHub Security Advisory published 2025-01-20. NVD baseline CVSS 4.7; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
4.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.7Exploit: NoneExposed: 0

A fix is available — apply it.

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

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period.

Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period.

CVSS v3
4.7
EG Score
4.7(medium)
EG Risk
—
EPSS
12.5%
KEV
Not listed

Published

January 20, 2025

Last Modified

July 14, 2026

Advisory Details (7)

Auto-updated Jul 19, 2026
Patch available.
generic

SSA-019113

https://cert-portal.siemens.com/productcert/html/ssa-019113.html
generic Patch Available

[SECURITY] [DLA 4076-1] linux-6.1 security update

https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
generic

Project Zero

https://project-zero.issues.chromium.org/issues/388499293
generic

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdb
generic

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7
generic

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10
generic

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/6b63308c28987c6010b1180c72a6db4df6c68033

Vendor Advisories for CVE-2025-21655(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(17)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-21.21) @ oracular2026-05-30ubuntu
ubuntulinux-tools-lowlatency-64k (6.11.0-1011.12) @ oracular2026-05-30ubuntu
ubuntulinux-tools-lowlatency-hwe-24.04-edge (6.11.0-1011.12~24.04.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-oem-24.04b (6.11.0-1017.17) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi (6.11.0-1010.10) @ oracular2026-05-30ubuntu
ubuntulinux-tools-realtime (6.8.1-1022.23) @ noble2026-05-30ubuntu
ubuntulinux-virtual (6.8.0-60.63) @ noble2026-05-30ubuntu
ubuntulinux-tools-nvidia-hwe-22.04-edge (6.8.0-1028.31~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-tools-gke (6.8.0-1025.29) @ noble2026-05-30ubuntu
ubuntulinux-tools-oem-24.04a (6.8.0-1028.28) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-nvidia (6.8.0-1016.17) @ noble2026-05-30ubuntu
ubuntulinux-tools-gkeop-6.8 (6.8.0-1012.14) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-realtime (6.8.0-2023.24) @ noble2026-05-30ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-60.63~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-tools-raspi (6.8.0-1028.32) @ noble2026-05-30ubuntu
ubuntulinux-tools-oracle-edge (6.8.0-1026.27~22.04.1) @ jammy2026-05-30ubuntu
redhatkernel-0:6.12.0-124.8.1.el10_12025-11-11redhat

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.

Additional Vendor Advisories

(16)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 10× in last 7d / 46× 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. 2026-07-22 14:07 UTCEPSS rescore
  2. 2026-07-22 14:07 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
  4. 2026-07-20 17:07 UTCEPSS rescore
  5. 2026-07-19 14:30 UTCEPSS rescore
  6. 2026-07-19 14:30 UTCEPSS rescore
  7. 2026-07-19 02:28 UTCEPSS rescore
  8. 2026-07-19 02:28 UTCEPSS rescore
  9. 2026-07-18 10:03 UTCEPSS rescore
  10. 2026-07-16 17:02 UTCEPSS rescore
  11. 2026-07-15 16:57 UTCEPSS rescore
  12. 2026-07-15 16:57 UTCEPSS rescore
  13. 2026-07-15 01:59 UTCEPSS rescore
  14. 2026-07-14 13:19 UTCNVD updateCVSS v3 → 4.7 · severity → MEDIUM
  15. 2026-07-14 13:11 UTCMITRE cvelistV5
  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 67 more
  1. 2026-07-07 13:45 UTCEPSS rescore
  2. 2026-07-07 12:51 UTCOSV refresh
  3. 2026-07-06 16:26 UTCEPSS rescore
  4. 2026-07-06 02:22 UTCEPSS rescore
  5. 2026-07-06 02:22 UTCEPSS rescore
  6. 2026-07-05 02:30 UTCEPSS rescore
  7. 2026-07-04 06:30 UTCEPSS rescore
  8. 2026-07-01 15:06 UTCEPSS rescore
  9. 2026-06-29 14:06 UTCEPSS rescore
  10. 2026-06-28 14:07 UTCEPSS rescore
  11. 2026-06-28 14:07 UTCEPSS rescore
  12. 2026-06-28 04:55 UTCEPSS rescore
  13. 2026-06-28 04:55 UTCEPSS rescore
  14. 2026-06-27 03:08 UTCEPSS rescore
  15. 2026-06-27 03:08 UTCEPSS rescore
  16. 2026-06-25 13:49 UTCEPSS rescore
  17. 2026-06-25 13:49 UTCEPSS rescore
  18. 2026-06-24 14:04 UTCEPSS rescore
  19. 2026-06-24 14:04 UTCEPSS rescore
  20. 2026-06-23 21:32 UTCEPSS rescore
  21. 2026-06-23 21:32 UTCEPSS rescore
  22. 2026-06-22 14:25 UTCEPSS rescore
  23. 2026-06-22 14:25 UTCEPSS rescore
  24. 2026-06-21 14:56 UTCEPSS rescore
  25. 2026-06-21 14:56 UTCEPSS rescore
  26. 2026-06-21 01:59 UTCEPSS rescore
  27. 2026-06-21 01:59 UTCEPSS rescore
  28. 2026-06-19 19:25 UTCEPSS rescore
  29. 2026-06-19 19:25 UTCEPSS rescore
  30. 2026-06-19 00:05 UTCOSV refresh
  31. 2026-06-18 17:52 UTCEPSS rescore
  32. 2026-06-18 17:52 UTCEPSS rescore
  33. 2026-06-17 17:52 UTCEPSS rescore
  34. 2026-06-16 17:52 UTCEPSS rescore
  35. 2026-06-16 17:52 UTCEPSS rescore
  36. 2026-06-15 17:48 UTCEPSS rescore
  37. 2026-06-14 23:17 UTCEPSS rescore
  38. 2026-06-13 22:59 UTCEPSS rescore
  39. 2026-06-12 23:11 UTCEPSS rescore
  40. 2026-06-11 13:59 UTCEPSS rescore
  41. 2026-06-10 22:18 UTCEPSS rescore
  42. 2026-06-10 13:22 UTCEPSS rescore
  43. 2026-06-08 14:16 UTCEPSS rescore
  44. 2026-06-08 14:16 UTCEPSS rescore
  45. 2026-06-07 15:24 UTCEPSS rescore
  46. 2026-06-07 15:24 UTCEPSS rescore
  47. 2026-06-06 13:47 UTCEPSS rescore
  48. 2026-06-06 13:47 UTCEPSS rescore
  49. 2026-06-05 22:46 UTCEPSS rescore
  50. 2026-06-05 22:46 UTCEPSS rescore
  51. 2026-06-05 06:10 UTCEPSS rescore
  52. 2026-06-05 06:10 UTCEPSS rescore
  53. 2026-06-04 13:11 UTCEPSS rescore
  54. 2026-06-04 13:11 UTCEPSS rescore
  55. 2026-06-02 20:12 UTCEPSS rescore
  56. 2026-06-02 20:12 UTCEPSS rescore
  57. 2026-06-01 13:51 UTCEPSS rescore
  58. 2026-06-01 13:51 UTCEPSS rescore
  59. 2026-05-31 22:30 UTCEPSS rescore
  60. 2026-05-31 22:30 UTCEPSS rescore
  61. 2026-05-31 00:16 UTCEPSS rescore
  62. 2026-05-31 00:16 UTCEPSS rescore
  63. 2026-05-30 13:04 UTCEG score recompute
  64. 2026-05-30 13:04 UTCVendor advisory
  65. 2026-05-30 13:04 UTCGHSA enrichment
  66. 2026-05-29 17:20 UTCOSV refresh
  67. 2026-05-29 13:44 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2025-21655?
CVE-2025-21655 is a medium vulnerability published on January 20, 2025. In the Linux kernel, the following vulnerability has been resolved: iouring/eventfd: ensure ioeventfd_signal() defers another RCU period ioeventfddo_signal() is invoked from an RCU callback, but when dropping the reference to the ioevfd, it calls ioeventfdfree() directly if the refcount drops to…
When was CVE-2025-21655 disclosed?
CVE-2025-21655 was first published in the National Vulnerability Database on January 20, 2025, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21655 actively exploited?
CVE-2025-21655 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 12.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-21655?
CVE-2025-21655 has a CVSS v3 base score of 4.7 (NVD).
How do I remediate CVE-2025-21655?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21655, 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.

Dependency Blast Radius

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