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CVE-2025-21759

7.8 · HIGH

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.

Published Feb 27, 2025CWE-416EPSS 7.80%

Overview

CVE-2025-21759 is a high-severity vulnerability. It was published on February 27, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/087c1faa594fa07a66933d750c0b2610aa1a2946Refgit.kernel.org/stable/c/0bf8e2f3768629d437a32cb824149e6e98254381Refgit.kernel.org/stable/c/81b25a07ebf53f9ef4ca8f3d96a8ddb94561dd5aRefgit.kernel.org/stable/c/8e92d6a413feaf968a33f0b439ecf27404407458

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21759?

CVE-2025-21759 is a high-severity vulnerability. It was published on February 27, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-21759?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-21759?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-21759?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21759 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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