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.
CSIRTS triage
- What
- Multiple vulnerabilities in the Linux kernel that may result in privilege escalation, denial of service, or information disclosure.
- Who is affected
- Debian systems running vulnerable Linux kernel versions.
- Urgency
- Multiple kernel vulnerabilities enabling privilege escalation and information leaks require urgent patching to protect system and data security.
- Action
- Apply the Debian security update DSA-6466-1 to the Linux kernel immediately.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.17% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 7% of all EPSS-scored CVEs.
Advisory coverage (2)
- unknownDSA-6466-1 linux - security updatedebian · 2026-08-25
- highCVE-2026-72111: In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register bounds…nvd · 2026-08-15
External references
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