Description
Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra.

This issue affects Core ROM: 2.1.0 through 2.1.1.
Published: 2026-08-04
Score: 5.6 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Wed, 05 Aug 2026 10:45:00 +0000

Type Values Removed Values Added
First Time appeared Caliptra
Caliptra core Rom
Vendors & Products Caliptra
Caliptra core Rom

Tue, 04 Aug 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 04 Aug 2026 00:15:00 +0000

Type Values Removed Values Added
Description Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra. This issue affects Core ROM: 2.1.0 through 2.1.1.
Title Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)
Weaknesses CWE-20
CWE-367
References
Metrics cvssV4_0

{'score': 5.6, 'vector': 'CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

Caliptra Core Rom
cve-icon MITRE

Status: PUBLISHED

Assigner: Caliptra

Published:

Updated: 2026-08-04T21:25:26.656Z

Reserved: 2026-06-09T23:30:36.611Z

Link: CVE-2026-11835

cve-icon Vulnrichment

Updated: 2026-08-04T19:24:16.679Z

cve-icon NVD

Status : Received

Published: 2026-08-04T00:16:40.047

Modified: 2026-08-04T20:16:48.413

Link: CVE-2026-11835

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-05T10:21:20Z

Weaknesses