What’s Vulnerable › Vulnerabilities

CVE-2025-21759: ipv6: mcast: extend RCU protection in igmp6_send()

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 7.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-02-27 · updated 2026-10-03
• Weakness: CWE-416

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.

Affected products

• Linux kernel: from 2.6.26 before 6.6.79; from 6.7 before 6.12.16; from 6.13 before 6.13.4; 6.14-rc1, 6.14-rc2 — fixed in 6.12.16, 6.13.4, 6.6.79

How to fix

Upgrade to a fixed version: Linux kernel 6.12.16, 6.13.4, 6.6.79. Check the vendor advisory for mitigations.

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

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