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 23, 2026, 11:49 p.m.
Last Modified :
June 23, 2026, 11:49 p.m.
Remotely Exploit :
No
Source :
Caliptra
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 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.
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.