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.
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.
Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Versions of Argo CD starting with v1.8.2 and prior to 2.3.13, 2.4.19, 2.5.6, and 2.6.0-rc-3 are vulnerable to an improper authorization bug causing the API to accept certain invalid tokens. OIDC providers include an aud (audience) claim in signed tokens. The value of that claim specifies the intended audience(s) of the token (i.e. the service or services which are meant to accept the token). Argo CD does validate that the token was signed by Argo CD's configured OIDC provider. But Argo CD does not validate the audience claim, so it will accept tokens that are not intended for Argo CD. If Argo CD's configured OIDC provider also serves other audiences (for example, a file storage service), then Argo CD will accept a token intended for one of those other audiences. Argo CD will grant the user privileges based on the token's groups claim, even though those groups were not intended to be used by Argo CD. This bug also increases the impact of a stolen token. If an attacker steals a valid token for a different audience, they can use it to access Argo CD. A patch for this vulnerability has been released in versions 2.6.0-rc3, 2.5.6, 2.4.19, and 2.3.13. There are no workarounds.
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
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 versions of ArgoCD starting from v2.4 have a bug where the ArgoCD repo-server component is vulnerable to a Denial-of-Service attack vector. Specifically, the said component extracts a user-controlled tar.gz file without validating the size of its inner files. As a result, a malicious, low-privileged user can send a malicious tar.gz file that exploits this vulnerability to the repo-server, thereby harming the system's functionality and availability. Additionally, the repo-server is susceptible to another vulnerability due to the fact that it does not check the extracted file permissions before attempting to delete them. Consequently, an attacker can craft a malicious tar.gz archive in a way that prevents the deletion of its inner files when the manifest generation process is completed.
Patches A patch for this vulnerability has been released in the following Argo CD versions:
v2.6.15 v2.7.14 v2.8.3
Workarounds The only way to completely resolve the issue is to upgrade.
Mitigations Configure RBAC (Role-Based Access Control) and provide access for configuring applications only to a limited number of administrators. These administrators should utilize trusted and verified Helm charts.
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 This vulnerability was found & reported by GE Vernova – Amit Laish.
The Argo team would like to thank these contributors for their responsible disclosure and constructive communications during the resolve of this issue
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 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.
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.