CVE-2023-23586: Due to a vulnerability in the io_uring subsystem, it is possible to leak kernel memory information to the user process. timens_install calls current_i...

Description

Due to a vulnerability in the io_uring subsystem, it is possible to leak kernel memory information to the user process. timens_install calls current_is_single_threaded to determine if the current process is single-threaded, but this call does not consider io_uring's io_worker threads, thus it is possible to insert a time namespace's vvar page to process's memory space via a page fault. When this time namespace is destroyed, the vvar page is also freed, but not removed from the process' memory, and a next page allocated by the kernel will be still available from the user-space process and can leak memory contents via this (read-only) use-after-free vulnerability. We recommend upgrading past version 5.10.161 or commit 788d0824269bef539fe31a785b1517882eafed93 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/io_uring

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

0.27%

18.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Linux	Linux Kernel	>= 5.6, < 5.10.161

References

Timeline

Published: Feb 17, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-23586?

Due to a vulnerability in the io_uring subsystem, it is possible to leak kernel memory information to the user process. timens_install calls current_is_single_threaded to determine if the current process is single-threaded, but this call does not consider io_uring's io_worker threads, thus it is possible to insert a time namespace's vvar page to process's memory space via a page fault. When this time namespace is destroyed, the vvar page is also freed, but not removed from the process' memory, and a next page allocated by the kernel will be still available from the user-space process and can leak memory contents via this (read-only) use-after-free vulnerability. We recommend upgrading past version 5.10.161 or commit 788d0824269bef539fe31a785b1517882eafed93 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/io_uring

How severe is CVE-2023-23586?

CVE-2023-23586 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2023-23586?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.