CVE-2026-72137

Published: August 18, 2026Last modified: August 18, 2026

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.

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References

• https://git.kernel.org/stable/c/226f4a490d1a938fc838d8f8c46a4eca864c0d78
• https://git.kernel.org/stable/c/5b0c4c916f202b8fd13d12afb6af62b385622f81
• https://git.kernel.org/stable/c/a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693
• https://git.kernel.org/stable/c/d0a4dc7efa825bce60a8da8f7d43c864a159abde