Fedora Account System
Red Hat Associate
Red Hat Customer
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.
Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026081531-CVE-2026-72137-5de5@gregkh/T
FYI: A working public exploit for CVE-2026-72137 has been released. Public exploit: https://github.com/NebuSec/CyberMeowfia/tree/main/security-research/Linux-CVE-2026-72137-ubuntu-7.0.0-28 A demonstration video showing exploitation is also publicly available: Demo video: https://x.com/nebusecurity/status/2092803089170637235 Relevant stable kernel fixes / reference backports: 6.12 stable backport: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=226f4a490d1a938fc838d8f8c46a4eca864c0d78 Mitigation: I am not aware of a practical module-blacklisting mitigation for this issue, as the relevant XFRM functionality is built into the kernel on the affected configurations. Given that a working public exploit is now available, could the RHEL 9 and RHEL 10 impact/fix status please be reviewed?
Correction to my previous comment: The commit I listed as a "6.12 stable backport": https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=226f4a490d1a938fc838d8f8c46a4eca864c0d78 is the original/upstream fix. The corresponding 6.12 stable fix is: https://git.kernel.org/stable/c/d0a4dc7efa825bce60a8da8f7d43c864a159abde Sorry for the incorrect label.