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CVE-2025-21759 — In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: extend RCU protection in…
Linux · Linux Kernel · Published 27 Feb 2025 · Modified 3 Oct 2026
Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: extend RCU protection in igmp6_send() igmp6_send() can be called without RTNL or RCU being held. Extend RCU protection so that we can safely fetch the net pointer and avoid a potential UAF. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection.
References
- https://git.kernel.org/stable/c/087c1faa594fa07a66933d750c0b2610aa1a2946
- https://git.kernel.org/stable/c/0bf8e2f3768629d437a32cb824149e6e98254381
- https://git.kernel.org/stable/c/638e8fe3563a82f298fe537a28d5342a97278cf1
- https://git.kernel.org/stable/c/6901bbb169e3add6c037218d996790cef6b3d650
- https://git.kernel.org/stable/c/7e0a818ecc4d62e7fb668ea02de0bfe8ba0b7dff
- https://git.kernel.org/stable/c/81b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5a
- https://git.kernel.org/stable/c/8e92d6a413feaf968a33f0b439ecf27404407458
What to do
- Check whether Linux Kernel is in your asset inventory.
- Patch in the next maintenance window; prioritise internet-facing systems.
- Record the decision in your risk register for audit evidence.
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Link: adminadda.com/cve/CVE-2025-21759