SB20260816152 - Use-after-free in Linux kernel ipv4

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-74561)

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 nh_rt_cache_flush in net/ipv4/nexthop.c when walking the f6i_list during nexthop replacement while IPv6 route add or delete operations mutate the list concurrently. A local user can trigger concurrent nexthop replacement and IPv6 route changes to cause a denial of service.

The issue occurs in the Linux kernel networking subsystem under a race condition involving RTNL-serialized nexthop replacement and list updates protected by nh->lock.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/44f53e4331a30fabc38a411fae7524341b618db3
• https://git.kernel.org/stable/c/4787a6d2629b4e8c0b6bacab1f75c1660eca44d9