What’s Vulnerable › Vulnerabilities

CVE-2025-21758: ipv6: mcast: add RCU protection to mld_newpack()

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 16.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-02-27 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: add RCU protection to mld_newpack() mld_newpack() can be called without RTNL or RCU being held. 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 5.15.179; from 5.16 before 6.1.129; from 6.2 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 5.15.179, 6.1.129, 6.12.16, 6.13.4, 6.6.79

How to fix

Upgrade to a fixed version: Linux kernel 5.15.179, 6.1.129, 6.12.16, 6.13.4. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1b91c597b0214b1b462eb627ec02658c944623f2
• https://git.kernel.org/stable/c/25195f9d5ffcc8079ad743a50c0409dbdc48d98a
• https://git.kernel.org/stable/c/29fa42197f26a97cde29fa8c40beddf44ea5c8f3
• https://git.kernel.org/stable/c/a527750d877fd334de87eef81f1cb5f0f0ca3373
• https://git.kernel.org/stable/c/d60d493b0e65647e0335e6a7c4547abcea7df8e9
• https://git.kernel.org/stable/c/e8af3632a7f2da83e27b083f787bced1faba00b1
• https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-082556.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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