CVE-2021-43837 Information
Description
vault-cli is a configurable command-line interface tool (and python library) to interact with Hashicorp Vault. In versions before 3.0.0 vault-cli features the ability for rendering templated values. When a secret starts with the prefix !template! vault-cli interprets the rest of the contents of the secret as a Jinja2 template. Jinja2 is a powerful templating engine and is not designed to safely render arbitrary templates. An attacker controlling a jinja2 template rendered on a machine can trigger arbitrary code making this a Remote Code Execution (RCE) risk. If the content of the vault can be completely trusted then this is not a problem. Otherwise if your threat model includes cases where an attacker can manipulate a secret value read from the vault using vault-cli then this vulnerability may impact you. In 3.0.0 the code related to interpreting vault templated secrets has been removed entirely. Users are advised to upgrade as soon as possible. For users unable to upgrade a workaround does exist. Using the environment variable VAULT_CLI_RENDER=false or the flag --no-render (placed between vault-cli and the subcommand e.g. vault-cli --no-render get-all) or adding render: false to the vault-cli configuration yaml file disables rendering and removes the vulnerability. Using the python library you can use: vault_cli.get_client(render=False) when creating your client to get a client that will not render templated secrets and thus operates securely.
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Reference
https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852 https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/ https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction Required
HIGH
Scope
NONE
Confidentiality Impact
CHANGED
Integrity Impact
HIGH
Availability Impact
HIGH
Base Score
HIGH
Base Severity
9.1
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