ip6mr: do not clone dst in ip6mr_cache_report()
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 5 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
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().
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.114, 6.18.57, 7.2.6, 7.3
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 6 | Affected | — |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Not affected: 3 products
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2026-90111
- 2026-10-03 Alias added: GHSA-4329-5qmc-m43g
- 2026-10-07 Affected versions changed · Red Hat
- 2026-10-07 CVSS score added · Red Hat
- 2026-10-16 Fix available: Linux/[email protected], Linux/Linux@f57b0fd1c62e1be274ee154ab7fb8ac4481b7f89 · CNA
- 2026-10-16 1 new reference · CNA
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Fix available: Linux/Linux@42ef371466d5648f5c9e8bc219f0af0a2c2bbf8c, Linux/[email protected], Linux/[email protected] +1 · CNA
- 2026-10-21 2 new references · CNA
- 2026-10-30 Affected versions changed · Red Hat
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@b50d3cfb8513e895cee453dd0f834deee6ccc231 · CNA
- 2026-10-30 1 new reference · CNA
References
Other 6
- https://git.kernel.org/stable/c/b50d3cfb8513e895cee453dd0f834deee6ccc231
- https://git.kernel.org/stable/c/7f8287f606c8c028d4224e85d95dc448c6d6d623
- https://git.kernel.org/stable/c/42ef371466d5648f5c9e8bc219f0af0a2c2bbf8c
- https://git.kernel.org/stable/c/f57b0fd1c62e1be274ee154ab7fb8ac4481b7f89
- https://git.kernel.org/stable/c/4a674afaae4136c71943aa3e35d433676fd40e8f
- https://git.kernel.org/stable/c/235b42b5860189eb8c27c36435ad932cae65a734
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Sources
- CVE-2026-90111 · CVE Program
- CVE-2026-90111 · NVD
- FIRST EPSS
- GHSA-4329-5qmc-m43g · GitHub Advisory Database · CC BY 4.0
- CVE-2026-90111 · Red Hat security data · CC BY 4.0
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