AES-256-GCM Authentication Tag Does Not Cover First Ciphertext Blocks When AAD Is Empty

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Summary

CVECVE-2026-6458
StatePUBLISHED
AssignerCaliptra
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-24 00:16:34 UTC
Updated2026-06-24 00:16:34 UTC
DescriptionMissing 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.

Risk And Classification

Primary CVSS: v4.0 5.1 MEDIUM from b01ddd03-5ef6-483b-b2c5-acba77f1a554

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/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

Problem Types: CWE-325 | CWE-325 CWE-325 Missing Cryptographic Step

VersionSourceTypeScoreSeverityVector
4.0b01ddd03-5ef6-483b-b2c5-acba77f1a554Secondary5.1MEDIUMCVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/C...
4.0CNACVSS5.1MEDIUMCVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS v4.0 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Sub Conf.
Low
Sub Integrity
Low
Sub Availability
None

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/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Caliptra Core Runtime Firmware affected 2.0.0 2.0.1 semver Not specified
CNA Caliptra Core Runtime Firmware affected 2.1.0 semver Not specified
CNA Caliptra Core Runtime Firmware unaffected 2.0.2 semver Not specified
CNA Caliptra Core Runtime Firmware unaffected 2.1.1 semver Not specified

References

ReferenceSourceLinkTags
github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-834g-h5x6-... b01ddd03-5ef6-483b-b2c5-acba77f1a554 github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: NVIDIA Offensive Security Research (OSR) team (en)

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