CVE-2026-90111 (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().

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CVSS v3.1 Score

7.8

HIGH

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

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/235b42b5860189eb8c27c36435ad932cae65a734 https://git.kernel.org/stable/c/4a674afaae4136c71943aa3e35d433676fd40e8f

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(). It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-90111? +

CVE-2026-90111 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-90111? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-90111