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.

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact Low

Subsequent System Integrity Impact Low

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Caliptra Core Runtime Firmware unaffected
Version Status Constraints
2.0.0 affected ≤ 2.0.1
2.1.0 affected —
2.0.2 unaffected —
2.1.1 unaffected —

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-834g-h5x6-2hqr cve-icon
History

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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Caliptra

Published:

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

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

Link: CVE-2026-6458

cve-icon Vulnrichment

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cve-icon NVD

No data.

cve-icon Redhat

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cve-icon OpenCVE Enrichment

Updated: 2026-06-24T03:30:05Z

Weaknesses