CVE-2026-72111

Status: UPDATED  |  Advisory ID: CVE-2026-72111

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reset register bounds before narrowing retval range in check_mem_access()

When the BPF verifier processes a context load of an LSM hook return

value, it calls __mark_reg_s32_range() to narrow the register to the

hook's valid range. However, __mark_reg_s32_range() intersects the new

range with the register's existing bounds using max_t()/min_t() rather

than replacing them.

If the destination register carries stale bounds from a prior instruction

(e.g. BPF_MOV64_IMM), the intersection can produce a range narrower than

reality. The verifier then believes it knows the register's exact value,

while at runtime the actual hook return value is loaded, creating a

verifier/runtime mismatch that can be used to bypass BPF memory safety

checks.

The else branch already calls mark_reg_unknown() to reset register state

before any narrowing. Apply the same reset in the is_retval path so

stale bounds are cleared before __mark_reg_s32_range() intersects. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References