SB20260815184 - Use-after-free in Linux kernel ipv4

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-74289)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 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]

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a use-after-free in fib_leaf_notify() and fib_info reference handling when dumping IPv4 fib_info entries under RCU during fib notifier processing. A local user can trigger network namespace cleanup or device reload operations that invoke affected fib notifier paths to cause a denial of service.

The issue was reported through the netdevsim notifier path, and IPv6 is not affected by the same condition.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/06b693d2eb6651a63ad85bad8673de3b7d4edd6d
• https://git.kernel.org/stable/c/676482da8d938ea72c26da0fc86af2d2ec238ab2