A flaw was found in ArgoCD. An improper authorization bug may allow an attacker to update at least one cluster secret, enabling them to change any other cluster secret. The attacker must know the URL for the targeted cluster and additionally it should be authenticated within the ArgoCD API server with enough privileges to update at least one cluster. A successful attack may lead to privilege escalations or denial of service.

Impact All versions of Argo CD starting from v2.6.0 have a bug where open web terminal sessions do not expire. This bug allows users to send any websocket messages even if the token has already expired. The most straightforward scenario is when a user opens the terminal view and leaves it open for an extended period. This allows the user to view sensitive information even when they should have been logged out already.

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

v2.6.14 v2.7.12 v2.8.1

Workarounds The only way to completely resolve the issue is to upgrade.

Mitigations Disable web-based terminal or define RBAC rules to it https://argo-cd.readthedocs.io/en/latest/operator-manual/webbasedterminal/

For more information If you have any questions or comments about this advisory: Open an issue in the Argo CD issue tracker or discussions Join us on Slack in channel #argo-cd

Credits

Thank you to bean.zhang (@zhlu32 ) of HIT-IDS ChunkL Team who discovered the issue and reported it confidentially according to our guidelines.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Argo CD has a Web-based terminal that allows users to get a shell inside a running pod, just as they would with kubectl exec. Starting in version 2.6.0, when the administrator enables this function and grants permission to the user p, role:myrole, exec, create, /, allow, even if the user revokes this permission, the user can still perform operations in the container, as long as the user keeps the terminal view open for a long time. Although the token expiration and revocation of the user are fixed, however, the fix does not address the situation of revocation of only user p, role:myrole, exec, create, /, allow permissions, which may still lead to the leakage of sensitive information. A patch for this vulnerability has been released in Argo CD versions 2.11.7, 2.10.16, and 2.9.21.

Impact All versions of Argo CD starting with v2.6.0-rc1 have an output sanitization bug which leaks repository access credentials in error messages. These error messages are visible to the user, and they are logged. The error message is visible when a user attempts to create or update an Application via the Argo CD API (and therefor the UI or CLI). The user must have applications, create or applications, update RBAC access to reach the code which may produce the error.

The user is not guaranteed to be able to trigger the error message. They may attempt to spam the API with requests to trigger a rate limit error from the upstream repository.

If the user has repositories, update access, they may edit an existing repository to introduce a URL typo or otherwise force an error message. But if they have that level of access, they are probably intended to have access to the credentials anyway.

Patches

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

v2.6.1

Workarounds

The only way to completely resolve the issue is to upgrade.

Mitigations

To mitigate the issue, make sure that your repo credentials have only least necessary privileges. For example, the credentials should not have push access, and they should not have access to more resources than what Argo CD actually needs (for example, a whole GitHub org when only one repo is needed).

To further mitigate the impact of a leaked write-capable repo credential, you could enable commit signature verification. Even if someone could push a malicious commit, the commit would not by synced.

You should also enforce least privileges in Argo CD RBAC. Make sure users only have repositories, update, applications, update, or applications, create access if they absolutely need it.

References

The problem was initially reported in a GitHub issue Argo CD RBAC configuration documentation

For more information

Open an issue in the Argo CD issue tracker or discussions Join us on Slack in channel #argo-cd