CVE-2025-21836: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 5.19, before 6.6.79 (fixed in 6.6.79); from 6.7, before 6.12.16 (fixed in 6.12.16); from 6.13, before 6.13.4 (fixed in 6.13.4); version 6.14 only

Published 2025-03-07. Last modified 2026-07-30.