CVE-2026-11835

Summary

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.

Affected Software

Weaknesses

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

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-49mm-5gq5-v97f

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