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Improper Validation of Array Index Affecting caddy-src package, versions <2.11.2-r2

Severity

 Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.03% (9th percentile)

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  • Snyk IDSNYK-MINIMOSLATEST-CADDYSRC-16042687
  • published14 Apr 2026
  • disclosed10 Apr 2026
Report a new vulnerability Found a mistake?

Introduced: 10 Apr 2026

NewCVE-2026-40097  (opens in a new tab)
CWE-129  (opens in a new tab)

How to fix?

Upgrade Minimos:latest caddy-src to version 2.11.2-r2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream caddy-src package and not the caddy-src package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

Step CA is an online certificate authority for secure, automated certificate management for DevOps. From 0.24.0 to before 0.30.0-rc3, 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. 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. This vulnerability is fixed in 0.30.0-rc3.