Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-11835

Severity CVSS v4.0:
MEDIUM
Type:
CWE-20 Input Validation
Publication date:
04/08/2026
Last modified:
04/08/2026

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.<br /> <br /> This issue affects Core ROM: 2.1.0 through 2.1.1.

Impact

Vector 4.0
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 CVSS v4.0 Severity and Metrics:

Base Score: 5.60 MEDIUM
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

Attack Vector (AV): Local
Attack Complexity (AC): High
Attack Requirements (AT): Present
Privileges Required (PR): High
User Interaction (UI): None
Confidentiality (VC): Low
Integrity (VI): High
Availability (VA): None
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
5.60
Severity 4.0
MEDIUM

References to Advisories, Solutions, and Tools