In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register bounds before narrowing retval range in check_mem_access()… (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 __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.
In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register bounds before narrowing retval range in check_mem_access()… (CVE-2026-72111)
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.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-vhcf-p8jc-x5f6
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-72111"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a808b76bf8831d539500131
Added to database: 08/15/2026, 15:53:26 UTC
Last updated: 08/15/2026, 15:54:50 UTC
Views: 1
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