Missing cryptographic step in Caliptra Core Firmware (aes_256_gcm_update module) results in an incorrect GCM authentication tag. When the streaming AES-256-GCM API is used with empty AAD, the hardware GHASH accumulator state is not saved after the first update call, causing the final tag to exclude the first batch of processed ciphertext. Ciphertext produced by that call may be modified without the tag reflecting the change. This issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.
History

Wed, 24 Jun 2026 16:45:00 +0000

Type Values Removed Values Added
First Time appeared Caliptra
Caliptra core Runtime Firmware
Vendors & Products Caliptra
Caliptra core Runtime Firmware

Wed, 24 Jun 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 24 Jun 2026 00:15:00 +0000

Type Values Removed Values Added
Description Missing cryptographic step in Caliptra Core Firmware (aes_256_gcm_update module) results in an incorrect GCM authentication tag. When the streaming AES-256-GCM API is used with empty AAD, the hardware GHASH accumulator state is not saved after the first update call, causing the final tag to exclude the first batch of processed ciphertext. Ciphertext produced by that call may be modified without the tag reflecting the change. This issue affects Core Runtime Firmware: from 2.0.0 through 2.0.1, 2.1.0.
Title AES-256-GCM Authentication Tag Does Not Cover First Ciphertext Blocks When AAD Is Empty
Weaknesses CWE-325
References
Metrics cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Caliptra

Published: 2026-06-23T23:49:44.591Z

Updated: 2026-06-24T13:15:03.109Z

Reserved: 2026-04-16T21:11:47.086Z

Link: CVE-2026-6458

cve-icon Vulnrichment

Updated: 2026-06-24T13:14:56.051Z

cve-icon NVD

No data.

cve-icon Redhat

No data.