Is CVE-2026-40097 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2026-40097, but active exploitation has not been confirmed.

Can CVE-2026-40097 be exploited remotely?

Yes. CVE-2026-40097 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40097?

CVE-2026-40097 has a CVSS score of 3.7 (LOW).

HOME VULNERABILITIESCVE-2026-40097

LOWPOC

CVE-2026-40097

CWE-129Published: April 10, 2026· Updated: Apr 13, 2026

3.7

CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-40097 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A proof-of-concept (PoC) exploit exists for CVE-2026-40097. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.