Double free in Linux kernel - CVE-2026-72137

Vulnerability identifier: #VU143450

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-72137

CWE-ID: CWE-415

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to double free in nat_keepalive_send() when handling send errors after handing a keepalive skb to the IPv4 or IPv6 output path. A local user can trigger an error during keepalive packet transmission to cause a denial of service.

The issue occurs because the skb may already have been consumed by the networking stack before an error is returned.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-oracle (Ubuntu package)
linux-gcp (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-nvidia-bos (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-gke (Ubuntu package)
linux-aws-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-azure (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-34.34
linux-realtime (Ubuntu package) - update to 7.0.0-34.34.1
linux-oracle (Ubuntu package) - update to 7.0.0-1012.12
linux-gcp (Ubuntu package) - update to 7.0.0-1013.13
linux-aws (Ubuntu package) - update to 7.0.0-1013.13
linux-raspi (Ubuntu package) - update to 7.0.0-1020.20
linux-nvidia (Ubuntu package) - update to 7.0.0-1025.26
linux-ibm (Ubuntu package) - update to 7.0.0-1014.14
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2022.23
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-34.34~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1013.13~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1012.12~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1014.14
linux-gke (Ubuntu package) - update to 7.0.0-1007.8
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1013.13~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1024.25~24.04.1
linux-azure-7.0 (Ubuntu package) - addressed in versions 7.0.0-1016.16~24.04.1, 7.0.0-1017.17~24.04.1
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1017.17

• 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

• Double free in Linux kernel xfrm
• Ubuntu update for linux-gcp
• Ubuntu update for linux
• Ubuntu update for linux-oracle-7.0
• Ubuntu update for linux-gke
• Ubuntu update for linux-azure-7.0
• Ubuntu update for linux-azure
• Ubuntu update for linux-nvidia-7.0, linux-nvidia-bos
• Ubuntu update for linux-nvidia