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CVE-2026-72137

9.8 · CRITICAL

In the Linux kernel, the following vulnerability has been resolved: xfrm: nat_keepalive: avoid double free on send error nat_keepalive_send() frees the keepalive skb whenever the IPv4 or IPv6 sen…

Published Aug 15, 2026EPSS 0.71%

Overview

CVE-2026-72137 is a critical-severity vulnerability. It was published on August 15, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

xfrm: nat_keepalive: avoid double free on send error

nat_keepalive_send() frees the keepalive skb whenever the IPv4 or IPv6

send helper reports an error.

That cleanup is only correct before the skb is handed to the output

path. Once ip_build_and_send_pkt() or ip6_xmit() takes ownership, the

networking stack may already have consumed the skb before returning an

error, so freeing it again is unsafe.

Handle the pre-handoff failure cases inside nat_keepalive_send_ipv4()

and nat_keepalive_send_ipv6(), where the caller still owns the skb, and

keep nat_keepalive_send() responsible only for family dispatch and the

unsupported-family cleanup path.

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/226f4a490d1a938fc838d8f8c46a4eca864c0d78Refgit.kernel.org/stable/c/5b0c4c916f202b8fd13d12afb6af62b385622f81Refgit.kernel.org/stable/c/a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693Refgit.kernel.org/stable/c/d0a4dc7efa825bce60a8da8f7d43c864a159abde

How CyberStrike helps

Frequently asked questions

What is CVE-2026-72137?

CVE-2026-72137 is a critical-severity vulnerability. It was published on August 15, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-72137?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-72137?

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-2026-72137?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-72137 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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