CVE-2025-21759: Linux Kernel

High severity, CVSS 7.8. EPSS: 7.8% chance of exploitation in the next 30 days.

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.

Affected products

• Linux Linux Kernel: from 2.6.26, before 6.6.79 (fixed in 6.6.79); from 6.7, before 6.12.16 (fixed in 6.12.16); from 6.13, before 6.13.4 (fixed in 6.13.4); version 6.14 only

Published 2025-02-27. Last modified 2026-10-03.