CVE-2026-98596 ipv6: Fix dst leak for uncached routes.

Not scored Published 18 Oct 2026 Updated 19 Oct 2026

A race condition in the Linux kernel IPv6 routing code can lead to a destination cache leak, potentially causing memory exhaustion and denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-98596?

CVE-2026-98596 is a vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

ipv6: Fix dst leak for uncached routes.

ip6_route_output_flags(), ip6_rt_put_flags(), and ip6_dst_check() detect an uncached route by list_empty(&rt->dst.rt_uncached), which replaced the static DST_NOCACHE flag check in commit a4c2fd7f7891 ("net: remove DST_NOCACHE flag").

When a device is unregistered, rt6_uncached_list_flush_dev() unlinks uncached routes tied to the device from rt6_uncached_list.

Previously, they were moved to another list with list_move() (__list_del_entry() + list_add()), and since commit 98aa546af5e4 ("inet: remove (struct uncached_list)->quarantine"), the routes are just unlinked with list_del_init().

If list_del_init() runs concurrently, list_empty() evaluates to true; ip6_route_output_flags() calls dst_hold_safe() incorrectly and ip6_rt_put_flags() skips ip6_rt_put(), leaking dst, and thus dev tied via rt->from as well.

The same race is partially fixed by commit 9a6f0c4d5796 ("dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()").

Let's check rt6->dst.rt_uncached_list instead.

Note that IPv4 does not have the same issue.

Which versions are affected by CVE-2026-98596?

How do I fix CVE-2026-98596?

Apply the vendor's patch.

Is CVE-2026-98596 being exploited?

There is no known exploitation of CVE-2026-98596 in the wild and no public exploit code.

Sources

Also known as BELL-CVE-2026-98596, DEBIAN-CVE-2026-98596, GHSA-gvvq-54cj-7xg4, UBUNTU-CVE-2026-98596.