Use-after-free in Linux kernel - CVE-2026-63911

Vulnerability identifier: #VU138747

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-2026-63911

CWE-ID: CWE-416

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 use-after-free in the iptfs state cloning logic in net/xfrm/xfrm_iptfs.c when destroying a cloned security association after a failed state migration. A local user can trigger state migration failure and queued packet handling to cause a denial of service.

The issue can involve shared cloned runtime objects, including queue, timer, lock, and reassembly or reorder state copied from the original security association.

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/7f83d174073234839aea176f265e517e0d50a1d2
• https://git.kernel.org/stable/c/9327252e04626d4bb02ca8c0c108fbe8eabf0c5a
• https://git.kernel.org/stable/c/dfb9f6cbfa9826655a49698cf90eb800fce2178e

• Use-after-free in Linux kernel xfrm
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia