# CVE-2026-5818

## Summary

- **CVE ID:** CVE-2026-5818
- **Severity:** HIGH
- **CVSS Score:** 7.2 (CVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H)
- **CWE:** CWE-253
- **Published:** Jun 23, 2026
- **Last Modified:** Jun 24, 2026

## 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 Products

- Caliptra — Core Runtime Firmware (2.0.0)
- Caliptra — Core Runtime Firmware (2.1.0)
- Caliptra — Core Runtime Firmware (2.0.2)
- Caliptra — Core Runtime Firmware (2.1.1)

## References

- [CNA](https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-456r-gcjr-6rxq)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.24%
- **EPSS Percentile:** 15.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._