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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-72111
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:21:25 UTC
Updated2026-08-17 06:18:10 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS: 0.001720000 probability, percentile 0.068830000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 bde92f65042ec14389782dd223f706bf6b59ce5d git Not specified
CNA Linux Linux affected 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 0993dc5fc619c0b25ab1310cb11d65e78351c0fe git Not specified
CNA Linux Linux affected 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 5a55f9aecc08990940e70f0c7048a80850c5a16a git Not specified
CNA Linux Linux affected 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 5e0b273e0a62cc04ec338c7b502797c66c2ed42a git Not specified
CNA Linux Linux affected 1050727d83e70449991c29dd1cf29fe936a63da3 git Not specified
CNA Linux Linux affected 27ca3e20fe80be85a92b10064dfeb56cb2564b1c git Not specified
CNA Linux Linux affected 6.10.13 6.11 semver Not specified
CNA Linux Linux affected 6.11.2 6.12 semver Not specified
CNA Linux Linux affected 6.12 Not specified
CNA Linux Linux unaffected 6.12 semver Not specified
CNA Linux Linux unaffected 6.12.103 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/0993dc5fc619c0b25ab1310cb11d65e78351c0fe 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5a55f9aecc08990940e70f0c7048a80850c5a16a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bde92f65042ec14389782dd223f706bf6b59ce5d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5e0b273e0a62cc04ec338c7b502797c66c2ed42a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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