CVE-2025-21836

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-03-07. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

A fix is available — apply it.

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

io_uring/kbuf: reallocate buf lists on upgrade

IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

March 7, 2025

Last Modified

August 5, 2026

Advisory Details (5)

Auto-updated Jul 30, 2026
No patch confirmed yet.
generic
https://u1f383.github.io/slides/talks/2025_Hexacon-Deja_Vu_in_Linux_io_uring_Breaking_Memory_Sharing_Again_After_Generations_of_Fixes.pdf
generic

io_uring/kbuf: reallocate buf lists on upgrade - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8802766324e1f5d414a81ac43365c20142e85603
generic

io_uring/kbuf: reallocate buf lists on upgrade - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/7d0dc28dae836caf7645fef62a10befc624dd17b
generic

io_uring/kbuf: reallocate buf lists on upgrade - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/2a5febbef40ce968e295a7aeaa5d5cbd9e3e5ad4
generic

io_uring/kbuf: reallocate buf lists on upgrade - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/146a185f6c05ee263db715f860620606303c4633

Patch Availability(10)

Vendor / EcosystemFixed in / PatchReleasedSource
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-lowlatency-hwe-24.04-edge (6.11.0-1014.15~24.04.1) @ noble2026-05-30ubuntu
ubuntulinux-virtual-6.8 (6.8.0-78.78) @ noble2026-05-30ubuntu
ubuntulinux-tools-ibm-lts-24.04 (6.8.0-1033.33) @ noble2026-05-30ubuntu
ubuntulinux-tools-raspi-6.8 (6.8.0-1035.39) @ noble2026-05-30ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1032.33) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1034.39~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2028.29) @ noble2026-05-30ubuntu
linuxKernel @ 6.6.79—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.

All Vendor Advisories

(9)

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 9× in last 7d / 44× 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.

Showing the most recent 100 of 108 total refreshes for this CVE.

  1. 2026-08-07 16:26 UTCEPSS rescore
  2. 2026-08-06 13:46 UTCEPSS rescore
  3. 2026-08-05 19:16 UTCEPSS rescore
  4. 2026-08-05 14:02 UTCEG score recompute
  5. 2026-08-05 14:02 UTCVendor advisory
  6. 2026-08-05 14:01 UTCGHSA enrichment
  7. 2026-08-04 15:09 UTCEPSS rescore
  8. 2026-08-04 10:37 UTCEPSS rescore
  9. 2026-08-02 02:25 UTCEPSS rescore
  10. 2026-08-01 04:15 UTCEPSS rescore
  11. 2026-07-30 16:27 UTCEPSS rescore
  12. 2026-07-30 07:19 UTCEG score recompute
  13. 2026-07-30 07:19 UTCGHSA enrichment
  14. 2026-07-30 01:29 UTCEPSS rescore
  15. 2026-07-28 15:35 UTCEPSS rescore
  16. 2026-07-27 14:12 UTCEPSS rescore
  17. 2026-07-26 14:53 UTCEPSS rescore
  18. 2026-07-25 14:17 UTCEPSS rescore
  19. 2026-07-24 14:17 UTCEPSS rescore
  20. 2026-07-24 12:41 UTCOSV refresh
  21. 2026-07-23 14:17 UTCEPSS rescore
  22. 2026-07-23 02:50 UTCEG score recompute
  23. 2026-07-22 14:07 UTCEPSS rescore
  24. 2026-07-22 14:07 UTCEPSS rescore
  25. 2026-07-21 15:24 UTCEPSS rescore
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  1. 2026-07-20 17:07 UTCEPSS rescore
  2. 2026-07-19 14:30 UTCEPSS rescore
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  4. 2026-07-19 02:28 UTCEPSS rescore
  5. 2026-07-19 02:28 UTCEPSS rescore
  6. 2026-07-18 10:03 UTCEPSS rescore
  7. 2026-07-16 17:02 UTCEPSS rescore
  8. 2026-07-15 16:57 UTCEPSS rescore
  9. 2026-07-15 16:57 UTCEPSS rescore
  10. 2026-07-15 01:59 UTCEPSS rescore
  11. 2026-07-13 22:29 UTCEPSS rescore
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  13. 2026-07-13 06:12 UTCEPSS rescore
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  15. 2026-07-12 05:46 UTCEPSS rescore
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  17. 2026-07-11 08:27 UTCEPSS rescore
  18. 2026-07-11 08:26 UTCEPSS rescore
  19. 2026-07-09 19:09 UTCEPSS rescore
  20. 2026-07-08 15:14 UTCEPSS rescore
  21. 2026-07-07 13:45 UTCEPSS rescore
  22. 2026-07-07 08:21 UTCOSV refresh
  23. 2026-07-06 16:26 UTCEPSS rescore
  24. 2026-07-06 02:22 UTCEPSS rescore
  25. 2026-07-06 02:22 UTCEPSS rescore
  26. 2026-07-05 02:30 UTCEPSS rescore
  27. 2026-07-04 06:30 UTCEPSS rescore
  28. 2026-07-01 15:06 UTCEPSS rescore
  29. 2026-06-29 14:06 UTCEPSS rescore
  30. 2026-06-28 14:07 UTCEPSS rescore
  31. 2026-06-28 14:07 UTCEPSS rescore
  32. 2026-06-28 04:55 UTCEPSS rescore
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  34. 2026-06-27 03:08 UTCEPSS rescore
  35. 2026-06-27 03:08 UTCEPSS rescore
  36. 2026-06-25 13:49 UTCEPSS rescore
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  38. 2026-06-24 14:04 UTCEPSS rescore
  39. 2026-06-24 14:04 UTCEPSS rescore
  40. 2026-06-23 21:32 UTCEPSS rescore
  41. 2026-06-23 21:32 UTCEPSS rescore
  42. 2026-06-22 14:25 UTCEPSS rescore
  43. 2026-06-22 14:25 UTCEPSS rescore
  44. 2026-06-21 14:56 UTCEPSS rescore
  45. 2026-06-21 14:56 UTCEPSS rescore
  46. 2026-06-21 01:59 UTCEPSS rescore
  47. 2026-06-21 01:59 UTCEPSS rescore
  48. 2026-06-19 19:25 UTCEPSS rescore
  49. 2026-06-19 19:25 UTCEPSS rescore
  50. 2026-06-18 19:13 UTCOSV refresh
  51. 2026-06-18 17:52 UTCEPSS rescore
  52. 2026-06-18 17:52 UTCEPSS rescore
  53. 2026-06-17 17:52 UTCEPSS rescore
  54. 2026-06-16 17:52 UTCEPSS rescore
  55. 2026-06-16 17:52 UTCEPSS rescore
  56. 2026-06-15 17:48 UTCEPSS rescore
  57. 2026-06-14 23:17 UTCEPSS rescore
  58. 2026-06-13 22:59 UTCEPSS rescore
  59. 2026-06-12 23:11 UTCEPSS rescore
  60. 2026-06-11 13:59 UTCEPSS rescore
  61. 2026-06-10 22:18 UTCEPSS rescore
  62. 2026-06-10 13:22 UTCEPSS rescore
  63. 2026-06-08 14:16 UTCEPSS rescore
  64. 2026-06-08 14:16 UTCEPSS rescore
  65. 2026-06-07 15:24 UTCEPSS rescore
  66. 2026-06-07 15:24 UTCEPSS rescore
  67. 2026-06-06 13:47 UTCEPSS rescore
  68. 2026-06-06 13:47 UTCEPSS rescore
  69. 2026-06-05 22:46 UTCEPSS rescore
  70. 2026-06-05 22:46 UTCEPSS rescore
  71. 2026-06-04 13:11 UTCEPSS rescore
  72. 2026-06-04 13:11 UTCEPSS rescore
  73. 2026-06-02 20:12 UTCEPSS rescore
  74. 2026-06-02 20:12 UTCEPSS rescore
  75. 2026-06-01 13:51 UTCEPSS rescore

Related CVEs(same product + same vendor)

Frequently asked(5)

What is CVE-2025-21836?
CVE-2025-21836 is a medium vulnerability published on March 7, 2025. In the Linux kernel, the following vulnerability has been resolved: io_uring/kbuf: reallocate buf lists on upgrade IORINGREGISTERPBUFRING can reuse an old struct iobuffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field…
When was CVE-2025-21836 disclosed?
CVE-2025-21836 was first published in the National Vulnerability Database on March 7, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-21836 actively exploited?
CVE-2025-21836 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 84.0% of all scored CVEs.
What is the CVSS score of CVE-2025-21836?
CVE-2025-21836 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21836?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-21836, 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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