CVE-2026-72111
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.18%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- EPSS
- 0.18% probability · 7th percentile
- CISA KEV
- Not listed
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.