CVE-2026-90111: Linux Vulnerability (CVSS 7.8)

Description

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().

Metrics

CVSS 3.1

7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.17%

6.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 67f415dd29063a5906c560051c00e42dcf01a4dd, < b50d3cfb8513e895cee453dd0f834deee6ccc231; >= 67f415dd29063a5906c560051c00e42dcf01a4dd, < 7f8287f606c8c028d4224e85d95dc448c6d6d623; >= 67f415dd29063a5906c560051c00e42dcf01a4dd, < 42ef371466d5648f5c9e8bc219f0af0a2c2bbf8c; >= 67f415dd29063a5906c560051c00e42dcf01a4dd, < f57b0fd1c62e1be274ee154ab7fb8ac4481b7f89; >= 67f415dd29063a5906c560051c00e42dcf01a4dd, < 4a674afaae4136c71943aa3e35d433676fd40e8f; >= 67f415dd29063a5906c560051c00e42dcf01a4dd, < 235b42b5860189eb8c27c36435ad932cae65a734
Linux	Linux	5.3

References

Timeline

Published: Sep 17, 2026
Last Modified: Oct 30, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-90111?

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().

How severe is CVE-2026-90111?

CVE-2026-90111 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2026-90111?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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