bpf: Reset register ID for BPF_END value tracking

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Summary

CVECVE-2026-43070
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-05 16:16:16 UTC
Updated2026-05-08 13:16:37 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Reset register ID for BPF_END value tracking When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an `r1 = r0` assignment), this tie must be broken. Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses. Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via `__mark_reg_known`.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.000130000 probability, percentile 0.022050000 (date 2026-05-11)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 4c03342e5ac532fb34d13a7b51dd7261dfc48963 a17443af874229408ce6b78e2c8a2b5adeb4b7d8 git Not specified
CNA Linux Linux affected d00ce96623a69a100ad79675d0e85fda3c50d89b 0d15c3611a2cc5d08993545d4032055ae10ae2c1 git Not specified
CNA Linux Linux affected 9d21199842247ab05c675fb9b6c6ca393a5c0024 a3125bc01884431d30d731461634c8295b6f0529 git Not specified
CNA Linux Linux affected 6.18.17 6.18.21 semver Not specified
CNA Linux Linux affected 6.19.7 6.19.11 semver Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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