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CVE-2026-5818

MCU Firmware Update Authentication Bypass on Caliptra Core

HIGH
7.2
CVSS Score
Published: June 23, 2026 at 11:50 PM UTC
Updated: October 25, 2026 at 11:10 PM UTC
1 product affected across 1 vendorCore Runtime Firmware

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Severity
HIGH7.2
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

Incorrect check of function return value in Caliptra Core Runtime Firmware (ActivateFirmwareCmd::activate_fw modules) allows bypass of Caliptra Core's verification of the MCU FW during a hitless update. This issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Core Runtime Firmware· Caliptra
90%
2.0.0 ≤ v ≤ 2.0.12.0.02.1.0
Vendor states this is fixed in 2.0.2 (unaffected)
Vendor states this is fixed in 2.1.1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

Source: cverecord
https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-456r-gcjr-6rxq

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.2HIGHCaliptra
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-253

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