SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityAwaiting Analysis

CVE-2026-5818

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.

HIGH 7.2EPSS 0.24%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.24%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public 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.

CVSS 4.0
7.2 HIGHCVSS:4.0/AV:A/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS
0.24% probability · 16th percentile
CISA KEV
Not listed
Weakness
CWE-253
Source
b01ddd03-5ef6-483b-b2c5-acba77f1a554

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.