id: GO-TEST-ID
modules:
    - module: github.com/argoproj/argo-cd
      versions:
        - introduced: 0.4.0
          fixed: 2.2.11
    - module: github.com/argoproj/argo-cd/v2
      versions:
        - introduced: 2.3.0
          fixed: 2.3.6
        - introduced: 2.4.0
          fixed: 2.4.5
      vulnerable_at: 2.4.4
summary: Argo CD certificate verification is skipped for connections to OIDC providers in github.com/argoproj/argo-cd
description: |-
    ### Impact

    All versions of Argo CD starting with v0.4.0 are vulnerable to an improper
    certificate validation bug which could cause Argo CD to trust a malicious (or
    otherwise untrustworthy) OIDC provider.

    (Note: external OIDC provider support was added in v0.11.0. Before that version,
    the notes below apply only to the bundled Dex instance.)

    You are impacted if 1) have SSO enabled and 2) insecure mode is _not_ enabled on
    the API server. In this case, certificate verification is skipped when
    connecting to your OIDC provider for the following tasks: verifying auth tokens
    on API requests and handling SSO login flows. If you are using the bundled Dex
    instance but have _not_ set the `--dex-server` flag on the API server to an
    HTTPS address, then certificate verification is not being skipped (because [TLS
    is not enabled by default for the bundled Dex
    instance](https://github.com/argoproj/argo-cd/issues/9424)).

    Argo CD sends requests to the configured OIDC provider (either the bundled Dex
    instance or an external provider) to 1) retrieve the [OpenID
    configuration](https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderConfig),
    2) to retrieve the OIDC provider's key set (at the location determined by the
    [OIDC provider's configured
    `jwks_uri`](https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderMetadata)),
    and 3) (during an SSO login) to exchange an authorization code for a token.

    (Note: Starting with v2.3.0, certificate verification is _not_ skipped when
    handling an SSO login flow if 1) you are not using the bundled Dex OIDC provider
    and 2) you have set `oidc.config.rootCA` in the `argocd-cm` ConfigMap.
    Certificate verification is still skipped when verifying tokens on API calls.)

    Skipping certificate verification when communicating with the OIDC provider
    opens Argo CD to a variety of risks. For example, if an attacker can
    successfully intercept, decrypt, and respond to requests bound for the
    configured OIDC provider (a machine-in-the-middle attack), they could
    theoretically issue a "valid" admin token. Verifying the OIDC provider's
    certificate provides an extra layer of protection against such an attack.

    ### Patches

    A patch for this vulnerability has been released in the following Argo CD
    versions:

    * v2.4.5
    * v2.3.6
    * v2.2.11

    **Note:**

    To preserve backwards compatibility, this patch adds a
    `oidc.tls.insecure.skip.verify` option to the `argocd-cm` ConfigMap. The default
    is `"false"`. Before resorting to setting this, you should try to get
    certificate verification to work. If you are using the bundled Dex instance,
    user your Argo CD API server's [TLS
    configuration](https://argo-cd.readthedocs.io/en/stable/operator-manual/tls/)
    since the API server acts as a reverse proxy to Dex. If you are using an
    external OIDC provider, [set the `rootCA`
    config](https://argo-cd.readthedocs.io/en/stable/operator-manual/user-management/#configuring-a-custom-root-ca-certificate-for-communicating-with-the-oidc-provider).

    If these fail, be sure you are aware of the risks before setting
    `oidc.tls.insecure.skip.verify: "true"`.

    ### Workarounds

    There is no complete workaround besides upgrading.

    #### Partial mitigation when using an external OIDC provider

    If you are using an external OIDC provider (not the bundled Dex instance), then
    you can mitigate the issue by setting the `oidc.config.rootCA` field in the
    `argocd-cm` ConfigMap. If your OIDC provider's certificate is self-signed or
    otherwise invalid, you must set the rootCA to a certificate that enables
    verification. If the OIDC provider's certificate passes _without_ an additional
    root CA, then you can set `oidc.config.rootCA` to a bogus non-empty string such
    as `"force cert verification"`. The API server will log a warning, but otherwise
    things should work fine.

    Example:

    ```yaml metadata: name: argocd-cm data: oidc.config: | ... rootCA: | force cert
    verification ```

    This mitigation _only_ forces certificate validation when the API server handles
    login flows. It does not force certificate verification when verifying tokens on
    API calls. To fully resolve the vulnerability, you must upgrade.

    ### References

    * [Argo CD SSO configuration
    documentation](https://argo-cd.readthedocs.io/en/stable/operator-manual/user-management/#sso)

    ### Credits

    @jannfis and @crenshaw-dev discovered the vulnerability when reviewing notes
    from ADA Logics' security audit of the Argo project sponsored by CNCF and
    facilitated by OSTIF. Thanks to Adam Korczynski and David Korczynski for their
    work on the audit.

    ### For more information

    * Open an issue in [the Argo CD issue
    tracker](https://github.com/argoproj/argo-cd/issues) or
    [discussions](https://github.com/argoproj/argo-cd/discussions)
    * Join us on [Slack](https://argoproj.github.io/community/join-slack) in channel
    #argo-cd
cves:
    - CVE-2022-31105
ghsas:
    - GHSA-7943-82jg-wmw5
references:
    - advisory: https://github.com/argoproj/argo-cd/security/advisories/GHSA-7943-82jg-wmw5
    - web: https://github.com/argoproj/argo-cd/releases/tag/v2.3.6
    - web: https://github.com/argoproj/argo-cd/releases/tag/v2.4.5
notes:
    - lint: 'description: possible markdown formatting (found ### )'
    - lint: 'description: possible markdown formatting (found [discussions](https://github.com/argoproj/argo-cd/discussions))'
    - lint: 'description: possible markdown formatting (found `--dex-server`)'
    - lint: 'modules[0] "github.com/argoproj/argo-cd": version 2.2.11 does not exist'
source:
    id: GHSA-7943-82jg-wmw5