Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-11835
StatePUBLISHED
AssignerCaliptra
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-04 00:16:40 UTC
Updated2026-08-04 20:16:48 UTC
DescriptionTime-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.

Risk And Classification

Primary CVSS: v4.0 5.6 MEDIUM from b01ddd03-5ef6-483b-b2c5-acba77f1a554

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.000820000 probability, percentile 0.002730000 (date 2026-08-04)

Problem Types: CWE-20 | CWE-367 | CWE-367 CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition | CWE-20 CWE-20 Improper Input Validation

VersionSourceTypeScoreSeverityVector
4.0b01ddd03-5ef6-483b-b2c5-acba77f1a554Secondary5.6MEDIUMCVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS5.6MEDIUMCVSS: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 Breakdown

Attack Vector
Local
Attack Complexity
High
Attack Requirements
Present
Privileges Required
High
User Interaction
None
Confidentiality
Low
Integrity
High
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Caliptra Core ROM affected 2.1.0 2.1.1 semver Not specified
CNA Caliptra Core ROM unaffected 2.1.2 semver Not specified

References

ReferenceSourceLinkTags
github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-49mm-5gq5-... b01ddd03-5ef6-483b-b2c5-acba77f1a554 github.com
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