CVE-2026-11835: CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition in Caliptra Core ROM
CVE-2026-11835 is a medium-severity TOCTOU race condition vulnerability in Caliptra Core ROM versions 2.1.0 through 2.1.1. It allows a compromised local attacker with high privileges to bypass secure boot by exploiting missing input validation in the UpdateResetFlow::run() function. The attacker can supply an unvalidated AXI staging address to modify firmware after verification but before loading, while attestation reports the original verified image digest, masking the compromise.
AI Analysis
Technical Summary
This vulnerability is a time-of-check time-of-use (TOCTOU) race condition combined with missing input validation in the Caliptra Core ROM's UpdateResetFlow::run() function in subsystem mode. A compromised MCU firmware with AXI manager access to unprotected SRAM can supply an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR. This enables modification of firmware between its verification and loading into ICCM. The attestation mechanism continues to report the originally verified image digest, hiding the unauthorized modification. The affected versions are Core ROM 2.1.0 through 2.1.1.
Potential Impact
An attacker with a compromised MCU firmware and AXI manager access can silently bypass the secure boot process, allowing unauthorized firmware modification without detection by attestation. This undermines the trustworthiness of the secure boot and attestation mechanisms, potentially enabling persistent firmware compromise.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary mitigation has been documented at this time.
CVE-2026-11835: CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition in Caliptra Core ROM
Description
CVE-2026-11835 is a medium-severity TOCTOU race condition vulnerability in Caliptra Core ROM versions 2.1.0 through 2.1.1. It allows a compromised local attacker with high privileges to bypass secure boot by exploiting missing input validation in the UpdateResetFlow::run() function. The attacker can supply an unvalidated AXI staging address to modify firmware after verification but before loading, while attestation reports the original verified image digest, masking the compromise.
CVSS v4.0
Score 5.6medium
Affected software
Caliptra
Core ROM
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability is a time-of-check time-of-use (TOCTOU) race condition combined with missing input validation in the Caliptra Core ROM's UpdateResetFlow::run() function in subsystem mode. A compromised MCU firmware with AXI manager access to unprotected SRAM can supply an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR. This enables modification of firmware between its verification and loading into ICCM. The attestation mechanism continues to report the originally verified image digest, hiding the unauthorized modification. The affected versions are Core ROM 2.1.0 through 2.1.1.
Potential Impact
An attacker with a compromised MCU firmware and AXI manager access can silently bypass the secure boot process, allowing unauthorized firmware modification without detection by attestation. This undermines the trustworthiness of the secure boot and attestation mechanisms, potentially enabling persistent firmware compromise.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary mitigation has been documented at this time.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Caliptra
- Date Reserved
- 2026-06-09T23:30:36.611Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a713369bf32cb7a347704bf
Added to database: 08/04/2026, 00:33:45 UTC
Last enriched: 08/11/2026, 18:05:48 UTC
Last updated: 09/17/2026, 22:01:32 UTC
Views: 73
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