Use-after-free in Linux kernel - CVE-2026-89791

Vulnerability identifier: #VU150502

CSH Severity: Low

CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-89791

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to escalate privileges.

The vulnerability exists due to use-after-free in perf event ring buffer handling when perf mmap revival races with the last munmap. A local user can race perf mmap and munmap operations to escalate privileges.

The issue is reachable by an unprivileged user under the default kernel.perf_event_paranoid=2 setting.

Linux kernel
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
kernel (Red Hat package)

Install security update from vendor's repository.

linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17
kernel (Red Hat package) - update to 6.12.0-211.68.1.el10_2

• https://git.kernel.org/stable/c/0c739f54f1c77f3a4643160cd2e031b6c2f2aab6
• https://git.kernel.org/stable/c/58a8108bc73de0740d5b88150465d6690ea5f85f
• https://git.kernel.org/stable/c/929cb3b9dc818dd9fa89d510d4ff2b255e42badd

• Use-after-free in Linux kernel events
• Red Hat Enterprise Linux 10 update for kernel
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more