CVE-2025-39963: io_uring: fix incorrect io_kiocb reference in io_link_skb

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-09 · updated 2026-10-19
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix incorrect io_kiocb reference in io_link_skb In io_link_skb function, there is a bug where prev_notif is incorrectly assigned using 'nd' instead of 'prev_nd'. This causes the context validation check to compare the current notification with itself instead of comparing it with the previous notification. Fix by using the correct prev_nd parameter when obtaining prev_notif.

Affected products

Linux kernel: from 6.10 before 6.12.49; from 6.13 before 6.16.9; 6.17-rc1, 6.17-rc2, 6.17-rc3, 6.17-rc4, 6.17-rc5, 6.17-rc6 — fixed in 6.12.49, 6.16.9

How to fix

Upgrade to a fixed version: Linux kernel 6.12.49, 6.16.9. Check the vendor advisory for mitigations.

References

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