What is CVE-2025-21836?

CVE-2025-21836 is a high-severity vulnerability in Linux. CVSS score: 7.8/10. Published 2025-03-07.

How severe is CVE-2025-21836?

High severity. CVSS v3 base score is 7.8 out of 10.

Is CVE-2025-21836 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Linux

CVE-2025-21836

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.

Published 2025-03-07 · last modified 2026-07-30.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (15.1th percentile), scored 2026-10-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.000

Affected products

Linux — versions 2fcabce2d7d34f69a888146dab15b36a917f09d4, 5.19, 0
Linux Kernel — versions 6.14

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Patch)
416baaa9-dc9f-4396-8d5f-8c081fb06d67

Frequently asked questions

What is CVE-2025-21836?: CVE-2025-21836 is a high-severity vulnerability in Linux. CVSS score: 7.8/10. Published 2025-03-07.
How severe is CVE-2025-21836?: High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2025-21836 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.