CVE-2026-5818
MCU Firmware Update Authentication Bypass on Caliptra Core
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.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
MCU Firmware Update Authentication Bypass on Caliptra Core
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.
- Record
CVE-2026-5818- CVSS 4.0
- 7.2 High
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 - Weakness
- CWE-253
- Updated
- 2026-11-02
EUVDEUVD-2026-38638
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.
- Record
EUVD-2026-38638- CVSS 4.0
- 7.2 High
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 - Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-5818- CVSS 4.0
- 7.2 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-253
- Updated
- 2026-11-02
OSV
MCU Firmware Update Authentication Bypass on Caliptra Core
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.
- Record
CVE-2026-5818- CVSS 4.0
- 7.2 High
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 - Weakness
- CWE-253
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-5818 is a high vulnerability (CVSS 7.2) in Caliptra Core Runtime Firmware, published June 23, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.24%, the 15th percentile. No source names a fixed version.