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Vulnerabilities

Vulnerability · CVE-2026-90111

ZDI-26-623: Linux Kernel IPv6 Multicast Routing Use-After-Free Local Privilege Escalation Vulnerability

Published Sep 9, 2026 · catalog updated Oct 15, 2026 · ZDI-26-623: Linux Kernel IPv6

Check if you run it

No confirmed exploitation is on record for CVE-2026-90111. EPSS is 0.17%. Act only if a listed version of ZDI-26-623: Linux Kernel IPv6 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (ZDI-26-623: Linux Kernel IPv6).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.17%
Remediation
Not established
Affected products
See sources for product scope

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().

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-90111

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-90111. EPSS is 0.17%. Act only if a listed version of ZDI-26-623: Linux Kernel IPv6 is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 17, 2026 · NIST NVD

    Detected

    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

  2. Oct 15, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-90111

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-90111

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-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 on

    nvd.nist.gov
  • Zero Day InitiativeCoordinated disclosureZDI-26-623

    This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The ZDI has assigned a CVSS rating of 8.8. The following CVEs are assigned: CVE-2026-90111.

    zerodayinitiative.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.