Always-Incorrect Control Flow Implementation in Linux kernel - CVE-2026-31413

Vulnerability identifier: #VU125836

CSH Severity: Low

CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-31413

CWE-ID: CWE-670

Exploitation vector: Local access

Exploit availability: Public exploit is available

The vulnerability allows a local user to access out-of-bounds map memory.

The vulnerability exists due to improper handling of scalar state forking in maybe_fork_scalars() when processing BPF_OR operations with a constant source operand. A local user can execute a crafted BPF program to access out-of-bounds map memory.

The issue is caused by a verifier/runtime divergence when the destination register has a signed range of [-1, 0].

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-fips (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-aws (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 6.8.0-136.136, 6.8.0-1046.50, 6.8.0-1059.67, 6.8.0-1064.72, 6.8.0-1064.72~22.04.1, 6.8.1-1056.57, 6.8.1-1056.57~22.04.2
linux-fips (Ubuntu package) - addressed in versions 6.8.0-136.136+fips2, 6.8.0-136.136.2, 6.8.0-136.136.2~22.04.1, 6.8.0-1058.61
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1030.31, 6.8.0-1033.34, 6.8.0-1061.62, 6.8.0-1061.62~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1058.61~22.04.1
linux-nvidia (Ubuntu package) - addressed in versions 6.8.0-1059.62, 6.8.0-1059.62.1, 6.8.0-1059.62~22.04.1
linux-aws-6.8 (Ubuntu package) - addressed in versions 6.8.0-1061.64+fips1, 6.8.0-1061.64~22.04.1
linux-aws (Ubuntu package) - update to 6.8.0-1061.64+1
linux-azure-fips (Ubuntu package) - update to 6.8.0-1063.71+fips2
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1064.72+fips1

• Exploit #12611 - bpf-research (CVE-2026-31413: BPF verifier soundness bug - container escape exploit) (April 17, 2026)

• https://git.kernel.org/stable/c/342aa1ee995ef5bbf876096dc3a5e51218d76fa4
• https://git.kernel.org/stable/c/58bd87d0e69204dbd739e4387a1edb0c4b1644e7
• https://git.kernel.org/stable/c/c845894ebd6fb43226b3118d6b017942550910c5
• https://git.kernel.org/stable/c/d13281ae7ea8902b21d99d10a2c8caf0bdec0455

• Always-Incorrect Control Flow Implementation in Linux kernel bpf
• Ubuntu update for linux
• Ubuntu update for linux-gcp-fips
• Ubuntu update for linux-oracle-6.8
• Ubuntu update for linux-fips
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure-fips
• Ubuntu update for linux-aws
• Ubuntu update for linux-aws-6.8
• Ubuntu update for linux-ibm