Impact
All versions of Argo CD starting with v0.11.0 are vulnerable to a variety of attacks when an SSO login is initiated from the Argo CD CLI or UI. The vulnerabilities are due to the use of insufficiently random values in parameters in Oauth2/OIDC login flows. In each case, using a relatively-predictable (time-based) seed in a non-cryptographically-secure pseudo-random number generator made the parameter less random than required by the relevant spec or by general best practices. In some cases, using too short a value made the entropy even less sufficient. (The specific weak parameters are listed in the References section.)
The attacks on login flows which are meant to be mitigated by these parameters are difficult to accomplish but can have a high impact (potentially granting an attacker admin access to Argo CD). The CVSS for this Security Advisory assumes the worst-case scenario.
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
Workarounds
There are no workarounds. You must upgrade to a patched version to resolve the vulnerability.
References
These are the insufficiently-random parameters:
1. (since 0.11.0) The state parameter generated by the argocd login command for Oauth2 login used a non-cryptographically secure source of entropy and generated a parameter that was too short to provide the entropy required in the spec. This parameter is a "recommended" part of the Oauth2 flow and helps protect against cross-site request forgery attacks. 2. (since 1.7.2, when PKCE was added) The codeverifier parameter generated by the argocd login command for Oauth2+PKCE login used a non-cryptographically secure source of entropy. The attacks mitigated by PKCE are complex but have been observed in the wild. 3. (since 0.11.0) The state parameter generated by the Argo CD API server during a UI-initiated Oauth2 login used a non-cryptographically secure source of entropy and generated a parameter that was too short to provide the entropy required in the spec. This parameter is a "recommended" part of the Oauth2 flow and helps protect against cross-site request forgery attacks. 4. (since 0.11.0) The nonce parameter generated by the Argo CD API server during a UI-initiated Oauth2 implicit flow login used a non-cryptographically secure source of entropy and generated a parameter that was too short to provide sufficient entropy. This parameter is a required part of the OIDC implicit login flow and helps protect against replay attacks.
Credits
Originally discovered by @jgwest. @jannfis and @crenshaw-dev re-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 or discussions Join us on Slack in channel #argo-cd
Impact
All unpatched versions of Argo CD starting with v1.0.0 are vulnerable to a cross-site scripting (XSS) bug allowing a malicious user to inject a javascript: link in the UI. When clicked by a victim user, the script will execute with the victim's permissions (up to and including admin).
The script would be capable of doing anything which is possible in the UI or via the API, such as creating, modifying, and deleting Kubernetes resources.
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
Workarounds
There are no completely-safe workarounds besides upgrading.
Mitigations:
1. Avoid clicking external links presented in the UI. Here is an example of an Application node with an external link:
!Application node in the Argo CD UI with an external link
The link's title is user-configurable. So even if you hover the link, and the tooltip looks safe, the link might be malicious. The only way to be certain that the link is safe is to inspect the page's source.
2. Carefully limit who has permissions to edit resource manifests (this is configured in RBAC).
References
Documentation for the external links feature
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. All versions of Argo CD starting with v1.3.0 are vulnerable to a symlink following bug allowing a malicious user with repository write access to leak sensitive YAML 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 Helm-type Application may commit a symlink which points to an out-of-bounds file. If the target file is a valid YAML file, the attacker can read the contents of that 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 YAML-formatted secrets which have been mounted as files on the repo-server. Patches for this vulnerability has been released in the following Argo CD versions: v2.4.1, v2.3.5, v2.2.10 and v2.1.16. If you are using a version >=v2.3.0 and do not have any Helm-type Applications you may disable the Helm config management tool as a workaround.