Always-Incorrect Control Flow Implementation in Linux kernel - CVE-2026-72256

Vulnerability identifier: #VU143183

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-2026-72256

CWE-ID: CWE-670

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 handling of template conntrack state in xt_cluster_mt() in the netfilter xt_cluster matcher when processing packets associated with a template conntrack. A local user can trigger packet processing that reaches xt_cluster_hash() with incomplete conntrack state to cause a denial of service.

The issue occurs when the raw table CT target attaches a template conntrack to skb->_nfct before normal conntrack processing.

Linux kernel
Ubuntu
linux-nvidia (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux (Ubuntu package)
linux-oem-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-nvidia (Ubuntu package) - addressed in versions 5.15.0-1112.113, 5.15.0.1112.112
linux-gcp-7.0 (Ubuntu package) - addressed in versions 7.0.0-38.38~24.04.4, 7.0.0-1013.13~24.04.1, 7.0.0-1014.14~24.04.1
linux (Ubuntu package) - addressed in versions 7.0.0-38.38, 7.0.0-38.38.1, 7.0.0-1008.9, 7.0.0-1013.13~24.04.1, 7.0.0-1014.14, 7.0.0-1015.15
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1015.15
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/07f9ddbf5e799c24a3a52ec9bd7b729a6f6d69d5
• https://git.kernel.org/stable/c/13ea4f86cf738c74be2146886ac261988a631e62
• https://git.kernel.org/stable/c/4558bd7b47c7be82dffd837f27be8ea3ecee557d
• https://git.kernel.org/stable/c/4cb8b5f586e41c187942291cc0938006077fa79e
• https://git.kernel.org/stable/c/5b2d4f0010018a7aa3495aa1dbf1b7a34011e7aa
• https://git.kernel.org/stable/c/5feba91006ec92da57acc1cc2e34df623b98541e
• https://git.kernel.org/stable/c/d5f9d050b0b267227c1f02f11021872c7768a9cc
• https://git.kernel.org/stable/c/fac2fdac3baad9ffd12b3b0bba4374d4b3585d54

• Always-Incorrect Control Flow Implementation in Linux kernel netfilter
• Ubuntu update for linux-gcp-7.0
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure-7.0
• Ubuntu update for linux
• Ubuntu update for linux-azure
• Ubuntu update for linux-oem-7.0