CVE Catalog

CVE-2026-90111

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

6th percentile - higher than 6% of all known CVEs

Summary

In the Linux kernel IPv6 multicast routing (ip6mr) subsystem, incoming packets attach a non-refcounted (NOREF) dst under RCU. When an ingress multicast packet misses MFC lookup, it is placed on 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, ip6mr_cache_report() executes dst_clone() on the freed dst entry, triggering a use-after-free.

Risk Assessment

This can lead to a slab use-after-free and kernel crash. The risk affects systems with IPv6 multicast routing enabled.

Recommendation

Update the Linux kernel to a version with the fix. Restrict the ability to send IPv6 multicast traffic from untrusted sources.

Related vulnerabilities

Original NVD description (English source)

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().

Vulnerability data from NVD (NIST) · CISA KEV · EPSS