Linux Kernel IPv6 network stack Vulnerability Rated 7.8 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-90111

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

ip6mr: do not clone dst in ip6mr_cache_report()

IPv6 input attaches a non-refcounted (NOREF) dst to skbs under RCU.

When an ingress multicast packet misses MFC lookup,

ip6mr_cache_unresolved() places the skb onto the unresolved queue,

escaping the receive-side RCU grace period.

If the underlying route is deleted and freed, and the MFC queue is later

resolved with a wrong parent interface, ip6_mr_forward() invokes

ip6mr_cache_report(..., MRT6MSG_WRONGMIF), which executes

dst_clone(skb_dst(pkt)) on the freed dst entry, triggering a slab

use-after-free.

Report packets queued to mroute6_sk (a raw socket) and netlink

notifications do not require an attached dst entry.

Fix this by:

1. Removing dst_clone() in ip6mr_cache_report() and ensuring report skbs

do not hold a dst.

2. Dropping skb_dst before queuing unresolved skbs in

ip6mr_cache_unresolved(), matching the fact that multicast

forwarding resolves outgoing routes anew via ip6_route_output(). (NVD)

What to Do

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

References