HCSEC-2023-21 - Nomad Caller ACL Token's Secret ID is Exposed to Sentinel

Bulletin ID: HCSEC-2023-21
Affected Products / Versions: Nomad and Nomad Enterprise 1.2.11 up to 1.5.6, and 1.4.10; fixed in 1.6.0, 1.5.7, and 1.4.11.
Publication Date: July 19, 2023

A vulnerability was identified in Nomad Enterprise (“Nomad”) such that the API caller’s ACL token secret ID is exposed to Sentinel policies. This vulnerability, CVE-2023-3299, affects Nomad from 1.2.11 up to 1.5.6, and 1.4.10 and was fixed in 1.6.0, 1.5.7, and 1.4.11.

Nomad provides an expressive policy-as-code system called Sentinel which can be used by administrators to enforce criteria for jobs submitted to a cluster. Authoring or enforcing these Sentinel policies in a cluster requires management-level (administrative) privileges.

Internal testing by the Nomad engineering team identified that Sentinel policies could access a caller’s ACL token secret ID, which is not strictly required to enforce policies.

This may allow a poorly specified policy to access the token’s secret ID and risk leaking it to command and API output if printed. Exploitation requires a management token to submit a Sentinel policy to a Nomad cluster, with the policy explicitly reading the secret from the token as nomad_acl_token.secret_id.

More requirements and recommendations for a secure Nomad deployment can be found in the security model.

Customers should evaluate the risk associated with this issue and consider upgrading to Nomad 1.6.0, 1.5.7, and 1.4.11, or newer.

See Nomad’s Upgrading for general guidance on this process.

This issue was identified by the Nomad engineering team.

We deeply appreciate any effort to coordinate disclosure of security vulnerabilities. For information about security at HashiCorp and the reporting of security vulnerabilities, please see https://hashicorp.com/security.