Description
In the Linux kernel, the following vulnerability has been resolved:

bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars

When regsafe() compares two scalar registers that both carry
BPF_ADD_CONST, check_scalar_ids() maps their full compound id
(aka base | BPF_ADD_CONST flag) as one idmap entry. However,
it never verifies that the underlying base ids, that is, with
the flag stripped are consistent with existing idmap mappings.

This allows construction of two verifier states where the old
state has R3 = R2 + 10 (both sharing base id A) while the current
state has R3 = R4 + 10 (base id C, unrelated to R2). The idmap
creates two independent entries: A->B (for R2) and A|flag->C|flag
(for R3), without catching that A->C conflicts with A->B. State
pruning then incorrectly succeeds.

Fix this by additionally verifying base ID mapping consistency
whenever BPF_ADD_CONST is set: after mapping the compound ids,
also invoke check_ids() on the base IDs (flag bits stripped).
This ensures that if A was already mapped to B from comparing
the source register, any ADD_CONST derivative must also derive
from B, not an unrelated C.
Published: 2026-06-24
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Sun, 28 Jun 2026 08:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Sat, 27 Jun 2026 03:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20

Sat, 27 Jun 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-386
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important


Wed, 24 Jun 2026 20:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20

Wed, 24 Jun 2026 17:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars When regsafe() compares two scalar registers that both carry BPF_ADD_CONST, check_scalar_ids() maps their full compound id (aka base | BPF_ADD_CONST flag) as one idmap entry. However, it never verifies that the underlying base ids, that is, with the flag stripped are consistent with existing idmap mappings. This allows construction of two verifier states where the old state has R3 = R2 + 10 (both sharing base id A) while the current state has R3 = R4 + 10 (base id C, unrelated to R2). The idmap creates two independent entries: A->B (for R2) and A|flag->C|flag (for R3), without catching that A->C conflicts with A->B. State pruning then incorrectly succeeds. Fix this by additionally verifying base ID mapping consistency whenever BPF_ADD_CONST is set: after mapping the compound ids, also invoke check_ids() on the base IDs (flag bits stripped). This ensures that if A was already mapped to B from comparing the source register, any ADD_CONST derivative must also derive from B, not an unrelated C.
Title bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-06-30T12:09:36.073Z

Reserved: 2026-06-09T07:44:35.383Z

Link: CVE-2026-53081

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-06-24T00:00:00Z

Links: CVE-2026-53081 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-28T13:45:06Z

Weaknesses