Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. All unpatched versions of Argo CD starting with 1.0.0 are vulnerable to an improper access control bug, allowing a malicious user to potentially escalate their privileges to admin-level. Versions starting with 0.8.0 and 0.5.0 contain limited versions of this issue. To perform exploits, an authorized Argo CD user must have push access to an Application's source git or Helm repository or sync and override access to an Application. Once a user has that access, different exploitation levels are possible depending on their other RBAC privileges. A patch for this vulnerability has been released in Argo CD versions 2.3.2, 2.2.8, and 2.1.14. Some mitigation measures are available but do not serve as a substitute for upgrading. To avoid privilege escalation, limit who has push access to Application source repositories or sync + override access to Applications; and limit which repositories are available in projects where users have update access to Applications. To avoid unauthorized resource inspection/tampering, limit who has delete, get, or action access to Applications.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Argo CD starting with version 0.7.0 and prior to versions 2.1.15m 2.2.9, and 2.3.4 is vulnerable to a symlink following bug allowing a malicious user with repository write access to leak sensitive files from Argo CD's repo-server. A malicious Argo CD user with write access for a repository which is (or may be) used in a directory-type Application may commit a symlink which points to an out-of-bounds file. Sensitive files which could be leaked include manifest files from other Applications' source repositories (potentially decrypted files, if you are using a decryption plugin) or any JSON-formatted secrets which have been mounted as files on the repo-server. A patch for this vulnerability has been released in Argo CD versions 2.3.4, 2.2.9, and 2.1.15. Users of versions 2.3.0 or above who do not have any Jsonnet/directory-type Applications may disable the Jsonnet/directory config management tool as a workaround.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. A vulnerability was found in Argo CD prior to versions 2.3.4, 2.2.9, and 2.1.15 that allows an attacker to spoof error messages on the login screen when single sign on (SSO) is enabled. In order to exploit this vulnerability, an attacker would have to trick the victim to visit a specially crafted URL which contains the message to be displayed. As far as the research of the Argo CD team concluded, it is not possible to specify any active content (e.g. Javascript) or other HTML fragments (e.g. clickable links) in the spoofed message. A patch for this vulnerability has been released in Argo CD versions 2.3.4, 2.2.9, and 2.1.15. There are currently no known workarounds.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. A critical vulnerability has been discovered in Argo CD starting with version 1.4.0 and prior to versions 2.1.15, 2.2.9, and 2.3.4 which would allow unauthenticated users to impersonate as any Argo CD user or role, including the admin user, by sending a specifically crafted JSON Web Token (JWT) along with the request. In order for this vulnerability to be exploited, anonymous access to the Argo CD instance must have been enabled. In a default Argo CD installation, anonymous access is disabled. The vulnerability can be exploited to impersonate as any user or role, including the built-in admin account regardless of whether it is enabled or disabled. Also, the attacker does not need an account on the Argo CD instance in order to exploit this. If anonymous access to the instance is enabled, an attacker can escalate their privileges, effectively allowing them to gain the same privileges on the cluster as the Argo CD instance, which is cluster admin in a default installation. This will allow the attacker to create, manipulate and delete any resource on the cluster. They may also exfiltrate data by deploying malicious workloads with elevated privileges, thus bypassing any redaction of sensitive data otherwise enforced by the Argo CD API. A patch for this vulnerability has been released in Argo CD versions 2.3.4, 2.2.9, and 2.1.15. As a workaround, one may disable anonymous access, but upgrading to a patched version is preferable.

Impact

All versions of Argo CD starting with v0.7.0 are vulnerable to an uncontrolled memory consumption bug, allowing an authorized malicious user to crash the repo-server service. The repo-server is a critical component of Argo CD, so crashing the repo-server effectively denies core Argo CD services (such as syncing Application updates).

To achieve denial of service, the attacker must be an authenticated Argo CD user authorized to deploy Applications from a repository which contains (or can be made to contain) a large file.

Patches

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

v2.4.1 v2.3.5 v2.2.10 v2.1.16

The patch introduces a new reposerver.max.combined.directory.manifests.size config parameter, which you should tune before upgrading in production. It caps the maximum total file size of .yaml/.yml/.json files in directory-type (raw manifest) Applications. The default max is 10M per Application. This max is designed to keep any single app from consuming more than 3G of memory in the repo-server (manifests consume more space in memory than on disk). The 300x ratio assumes a maliciously-crafted manifest file. If you only want to protect against accidental excessive memory use, it is probably safe to use a smaller ratio.

If your organization uses directory-type Applications with very many manifests or very large manifests then check the size of those manifests and tune the config parameter before deploying this change to production. When testing, make sure to do a "hard refresh" in either the CLI or UI to test your directory-type App. That will make sure you're using the new max logic instead of relying on cached manifest responses from Redis.

Workarounds

There is no workaround besides upgrading.

To mitigate the issue, carefully limit 1) who can configure repos (determined by RBAC), 2) which repos are allowed (determined by Project limitations), and 3) who has push access to those repos (determined by your SCM provider configuration).

Credits

Disclosed by ADA Logics in a 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 or discussions Join us on Slack in channel #argo-cd

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Argo CD starting with version 0.4.0 and prior to 2.2.11, 2.3.6, and 2.4.5 is vulnerable to an improper certificate validation bug which could cause Argo CD to trust a malicious (or otherwise untrustworthy) OpenID Connect (OIDC) provider. A patch for this vulnerability has been released in Argo CD versions 2.4.5, 2.3.6, and 2.2.11. There are no complete workarounds, but a partial workaround is available. Those who use an external OIDC provider (not the bundled Dex instance), can mitigate the issue by setting the oidc.config.rootCA field in the argocd-cm ConfigMap. 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.

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Argo CD starting with 2.3.0 and prior to 2.3.6 and 2.4.5 is vulnerable to a cross-site scripting (XSS) bug which could allow an attacker to inject arbitrary JavaScript in the /auth/callback page in a victim's browser. This vulnerability only affects Argo CD instances which have single sign on (SSO) enabled. The exploit also assumes the attacker has 1) access to the API server's encryption key, 2) a method to add a cookie to the victim's browser, and 3) the ability to convince the victim to visit a malicious /auth/callback link. The vulnerability is classified as low severity because access to the API server's encryption key already grants a high level of access. Exploiting the XSS would allow the attacker to impersonate the victim, but would not grant any privileges which the attacker could not otherwise gain using the encryption key. A patch for this vulnerability has been released in the following Argo CD versions 2.4.5 and 2.3.6. There is currently no known workaround.

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.

All unpatched versions of Argo CD starting with v1.0.0 are vulnerable to an improper access control bug, allowing a malicious user to potentially escalate their privileges to admin-level.