Use-after-free in Linux kernel - CVE-2026-74561

Vulnerability identifier: #VU143220

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-2026-74561

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

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.

Linux kernel
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)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
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

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

• Use-after-free in Linux kernel ipv4
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more