Use-after-free in Linux kernel - CVE-2026-63823
Published: July 21, 2026
Vulnerability identifier: #VU138830
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63823
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to use-after-free in request_key_auth handling in the Linux kernel key management subsystem when processing KEYCTL_INSTANTIATE_IOV or related key instantiation and rejection paths concurrently with request_key() completion. A local user can trigger concurrent key operations to cause a denial of service.
The issue occurs because the request_key_auth payload can be freed after helper completion while another path later resumes and accesses rka->target_key.
Affected software
Linux kernel
How to mitigate CVE-2026-63823
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/35ab4db86774d82389e4b9559e26ab7f68d8e395
- https://git.kernel.org/stable/c/4982bfabce6b33b3c9eddb4fb900fe5568b7cf91
- https://git.kernel.org/stable/c/708709c65a1832a99b0eef8ae46e343ddaca3d06
- https://git.kernel.org/stable/c/7216ce8cb12fee44e309503955bb83806b106129
- https://git.kernel.org/stable/c/83c0a1cb296d955d5f4d1f0bd8a769ba8ed8c29f
- https://git.kernel.org/stable/c/d8274181b0f28d450b42489723a5ba81042158d7
- https://git.kernel.org/stable/c/f9b68632ac93cc742f2e411021c4dbfe452ea0c2
- https://git.kernel.org/stable/c/fd15b457a86939c38aa12116adabd8ff686c5e51