GHSA-9qq8-cgcv-qmc9

Source

https://github.com/advisories/GHSA-9qq8-cgcv-qmc9

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-9qq8-cgcv-qmc9/GHSA-9qq8-cgcv-qmc9.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-9qq8-cgcv-qmc9

Aliases

CVE-2026-40097

Downstream

MINI-c5wr-7mfx-jwmr

MINI-j347-365p-qh3g

Published

2026-04-10T20:18:08Z

Modified

2026-04-10T20:33:50.157870Z

Severity

3.7 (Low) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L CVSS Calculator

Summary

Step CA affected by an index out of bounds panic in TPM attestation EKU validation

Details

Summary

An attacker can trigger an index out-of-bounds panic in Step CA by sending a crafted attestation key (AK) certificate with an empty Extended Key Usage (EKU) extension during TPM device attestation.

Details

When processing a device-attest-01 ACME challenge using TPM attestation, Step CA validates that the AK certificate contains the tcg-kp-AIKCertificate Extended Key Usage OID. During this validation, the EKU extension value is decoded from its ASN.1 representation and the first element is checked. A crafted certificate could include an EKU extension that decodes to an empty sequence, causing the code to panic when accessing the first element of the empty slice.

This vulnerability is only reachable when a device-attest-01 ACME challenge with TPM attestation is configured. Deployments not using TPM device attestation are not affected.

Mitigations

If you are unable to upgrade to v0.30.0 or newer, the attack can be mitigated by disabling or removing any ACME provisioners that use TPM device attestation (device-attest-01).

Fix

In v0.30.0, a bounds check was added to validateAKCertificateExtendedKeyUsage so that an empty EKU sequence is treated as a validation failure rather than causing a panic.

Acknowledgements

This issue was identified and reported by @1seal (Oleh Konko).

Embargo List

If your organization runs Step CA in production and would like advance, embargoed notification of future security updates, visit https://u.step.sm/disclosure to request inclusion on our embargo list.

Stay safe, and thank you for helping us keep the ecosystem secure.

Database specific

{
    "github_reviewed": true,
    "nvd_published_at": "2026-04-10T17:17:12Z",
    "cwe_ids": [
        "CWE-129"
    ],
    "github_reviewed_at": "2026-04-10T20:18:08Z",
    "severity": "LOW"
}

References

Affected packages

Go / github.com/smallstep/certificates

Package

Name: github.com/smallstep/certificates; View open source insights on deps.dev
Purl: pkg:golang/github.com/smallstep/certificates

Affected ranges

Type: SEMVER
Events: Introduced

0.24.0

Fixed

0.30.0

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-9qq8-cgcv-qmc9/GHSA-9qq8-cgcv-qmc9.json"