CVE-2026-6458
AES-256-GCM Authentication Tag Does Not Cover First Ciphertext Blocks When AAD Is Empty
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.
INFO
Published Date :
June 24, 2026, 12:16 a.m.
Last Modified :
June 25, 2026, 4:14 p.m.
Remotely Exploit :
No
Source :
b01ddd03-5ef6-483b-b2c5-acba77f1a554
Affected Products
The following products are affected by CVE-2026-6458
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | MEDIUM | b01ddd03-5ef6-483b-b2c5-acba77f1a554 | ||||
| CVSS 4.0 | MEDIUM | b01ddd03-5ef6-483b-b2c5-acba77f1a554 |
Solution
- Update Caliptra Core Firmware to a non-vulnerable version.
- Verify the GHASH accumulator state is saved correctly.
- Ensure all ciphertexts are authenticated by the updated tag.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6458.
| URL | Resource |
|---|---|
| https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-834g-h5x6-2hqr |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6458 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6458
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6458 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6458 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 24, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-6458', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-24T13:14:19.562293Z'} -
New CVE Received by b01ddd03-5ef6-483b-b2c5-acba77f1a554
Jun. 24, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Caliptra', 'modules': ['aes_256_gcm_update'], 'product': 'Core Runtime Firmware', 'versions': [{'status': 'affected', 'version': '2.0.0', 'versionType': 'semver', 'lessThanOrEqual': '2.0.1'}, {'status': 'affected', 'version': '2.1.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '2.0.2', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '2.1.1', 'versionType': 'semver'}], 'packageName': 'Core Runtime Firmware', 'collectionURL': 'https://github.com/chipsalliance/caliptra-sw', 'defaultStatus': 'unaffected'}] 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. Added CVSS V4.0 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 Added CWE CWE-325 Added Reference https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-834g-h5x6-2hqr