SB20260928157 - Improper input validation in Linux kernel bpf

Description

This security bulletin contains information about 1 vulnerability.

1) Improper input validation (CVE-ID: CVE-2026-98034)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to bypass BPF verifier pointer-type checks.

The vulnerability exists due to improper state precision tracking in check_map_kptr_access() when verifying BPF programs that store a known-zero scalar in an untrusted kptr field. A local user can craft a program that causes state pruning to accept a path with a nonzero scalar and treat attacker-controlled bits as a PTR_TO_BTF_ID to bypass BPF verifier pointer-type checks.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/86168208737bdd267d92d855d453d1d2f840df19
• https://git.kernel.org/stable/c/ecdc5043794c9184aa8e6c814603899479c46b35