Linux Kernel IPv6 network stack Vulnerability Rated 8.8 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-74561

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

nexthop: avoid unlocked f6i_list walk in nh_rt_cache_flush

nh_rt_cache_flush() walks nh->f6i_list during an RTNL-serialized nexthop

replace without holding nh->lock, racing the unlocked IPv6 route

add/delete that mutate the list under nh->lock and free fib6_info

entries (nh_rt_cache_flush() is inlined into rtm_new_nexthop()):

BUG: KASAN: slab-use-after-free in nh_rt_cache_flush (net/ipv4/nexthop.c:2243)

Read of size 8 at addr ffff888012953e18 by task exploit/146

nh_rt_cache_flush (net/ipv4/nexthop.c:2243)

replace_nexthop (net/ipv4/nexthop.c:2610)

rtm_new_nexthop (net/ipv4/nexthop.c:3323)

rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)

Unlike the other f6i_list walks, this one bumps each route's sernum via

fib6_update_sernum_upto_root(), which needs tb6_lock; taking nh->lock

around it would invert the established tb6_lock -> nh->lock order and

deadlock. As the only purpose is to invalidate cached dsts, bump the

IPv6 sernum for the whole netns with rt_genid_bump_ipv6() instead,

mirroring the rt_cache_flush() already done for IPv4 just above. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References