CVE-2021-43837: Vault cli Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q34h-97wf-8r8j",
  "modified" : "2024-11-18T22:46:40Z",
  "published" : "2021-12-16T21:02:12Z",
  "aliases" : [ "CVE-2021-43837" ],
  "summary" : "vault-cli contains possible RCE when reading user-defined data",
  "details" : "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nvault-cli features the ability for rendering templated values (as explained in the [documentation](https://github.com/peopledoc/vault-cli/blob/2.2.1/docs/howto/templated_secrets.rst)). When a secret starts with the prefix `!template!`, vault-cli interprets the rest of the contents of the secret as a Jinja2 template.\nJinja2 is a powerful templating engine and it's 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.\nIf 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.\n\nThis does not impact `vault` itself, except for the fact that the attacker, having an RCE on the machine that executes `vault-cli`, may abuse the token that `vault-cli` uses, to read, write or delete other data from the vault.\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nIn 3.0.0, the code related to interpreting vault templated secrets has been removed entirely.\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nUsing 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.\nUsing 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.\n\n### References\n_Are there any links users can visit to find out more?_\n\nHere's an article explaining how jinja2 templates might be exploited to have side effects: https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2/\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [the vault-cli repo](https://github.com/peopledoc/vault-cli/issues/new)\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "vault-cli"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.7.0"
      }, {
        "fixed" : "3.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/peopledoc/vault-cli/security/advisories/GHSA-q34h-97wf-8r8j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-43837"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/peopledoc/vault-cli/pull/198"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/peopledoc/vault-cli/commit/3ba3955887fd6b7d4d646c8b260f21cebf5db852"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/peopledoc/vault-cli"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/peopledoc/vault-cli/releases/tag/3.0.0"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/vault-cli/PYSEC-2021-853.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://podalirius.net/en/publications/grehack-2021-optimizing-ssti-payloads-for-jinja2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-74", "CWE-94" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-12-16T19:28:49Z",
    "nvd_published_at" : "2021-12-16T19:15:00Z"
  }
}