CVE-2026-5818 MCU Firmware Update Authentication Bypass on Caliptra Core
Attackers can bypass MCU firmware verification during hitless updates due to incorrect return value checks in Caliptra Core Runtime Firmware.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-5818?
CVE-2026-5818 is a high-severity authentication bypass vulnerability in Caliptra Core Runtime Firmware, published on 23 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-253
Which versions are affected by CVE-2026-5818?
How do I fix CVE-2026-5818?
No fix has been published for CVE-2026-5818 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-5818 being exploited?
There is no known exploitation of CVE-2026-5818 in the wild and no public exploit code.
Sources
Also known as GHSA-456r-gcjr-6rxq.