Use-after-free in Linux kernel - CVE-2026-90303
Published: September 18, 2026
Vulnerability identifier: #VU151186
CSH Severity: Low
CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-90303
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 show_pte() when handling user faults concurrently with munmap() calls. A local user can trigger a user fault while another thread in the same process calls munmap() to cause a denial of service.
Exploitation requires CONFIG_DEBUG_USER=y and the user_debug=31 command-line setting.
Affected software
Linux kernel
How to mitigate CVE-2026-90303
Install security update from vendor's repository.
External References
- https://git.kernel.org/stable/c/07e4d5380f2a844ab7a1b440dde350caf561cbb0
- https://git.kernel.org/stable/c/1039bffd6ae9c75b42b7d148d6c1106134107b66
- https://git.kernel.org/stable/c/2a14d7797a49a47bccd1a9327fd69da838dcb0dd
- https://git.kernel.org/stable/c/59bbf86d0ff9373bfa033ca123c1e924f09f1eba
- https://git.kernel.org/stable/c/63e3c958a602d0896a101a897c2361878c266ca7
- https://git.kernel.org/stable/c/720408d98d9fb3c91a12090436734c8c61f04545
- https://git.kernel.org/stable/c/ab14f07952adfe735d86a53518f8cd576dfd5892
- https://git.kernel.org/stable/c/c71f9a56520b419e55d173052629f2324deb5549