Improper resource shutdown or release in Linux kernel - CVE-2026-63970

Vulnerability identifier: #VU138672

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-2026-63970

CWE-ID: CWE-404

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 improper resource shutdown or release in virtio_transport_alloc_skb() in the vsock/virtio transport when processing fixed-buffer vectored zerocopy input that hits MAX_SKB_FRAGS. A local user can trigger a partial attachment of managed fragments to cause a denial of service.

Exploitation occurs on the rollback path after io_sg_from_iter() returns -EMSGSIZE, causing an skb with managed fragment references but no bound uarg to be freed through the ordinary fragment unref path.

Linux kernel
Debian Linux
Ubuntu
linux (Debian package)
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 (Debian package) - update to 6.12.100-1
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/1e584c304cfb94a759417130b1fc6d30b30c4cce
• https://git.kernel.org/stable/c/5d317573f1d48e76cce5fb6250452b6e4102e0fb
• https://git.kernel.org/stable/c/b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d

• Improper resource shutdown or release in Linux kernel vmw_vsock
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Debian update for linux
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia