===================================================================== CERT-Renater Note d'Information No. 2023/VULN027 _____________________________________________________________________ DATE : 26/01/2023 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Systems running argo-cd versions prior to 2.6.0-rc5, v2.5.8, v2.4.20, v2.3.14. ===================================================================== https://github.com/argoproj/argo-cd/security/advisories/GHSA-q9hr-j4rf-8fjc https://github.com/argoproj/argo-cd/security/advisories/GHSA-6p4m-hw2h-6gmw _____________________________________________________________________ JWT audience claim is not verified Critical crenshaw-dev published GHSA-q9hr-j4rf-8fjc Jan 25, 2023 Package github.com/argoproj/argo-cd (Go) Affected versions 1.8.2 through 2.6.0-rc4, v2.5.7, v2.4.18, v2.3.13 Patched versions 2.6.0-rc5, v2.5.8, v2.4.20, v2.3.14 Description Impact All versions of Argo CD starting with v1.8.2 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 blast radius of a stolen token. If an attacker steals a valid token for a different audience, they can use it to access Argo CD. Patches A patch for this vulnerability has been released in the following Argo CD versions: v2.6.0-rc5 v2.5.8 v2.4.20 v2.3.14 The patch introduces a new allowedAudiences to the OIDC config block. By default, the client ID is the only allowed audience. Users who want Argo CD to accept tokens intended for a different audience may use allowedAudiences to specify those audiences. apiVersion: v1 kind: ConfigMap metadata: name: argocd-cm data: oidc.config: | name: Example allowedAudiences: - audience-1 - audience-2 - argocd-client-id # If `allowedAudiences` is non-empty, Argo CD's client ID must be explicitly added if you want to allow it. Even though the OIDC spec requires the audience claim, some tokens may not include it. To avoid a breaking change in a patch release, versions < 2.6.0 of Argo CD will skip the audience claim check for tokens that have no audience. In versions >= 2.6.0, Argo CD will reject all tokens which do not have an audience claim. Users can opt into the old behavior by setting an option: apiVersion: v1 kind: ConfigMap metadata: name: argocd-cm data: oidc.config: | name: Example skipAudienceCheckWhenTokenHasNoAudience: true Workarounds There is no workaround besides upgrading. Credits The Argo CD team would like to express their gratitude to Vladimir Pouzanov (@farcaller) from Indeed, who discovered the issue, reported it confidentially according to our guidelines, and actively worked with the project to provide a remedy. Many thanks to Vladimir! References How to configure OIDC in Argo CD OIDC spec section discussing the audience claim JWT spec section discussing the audience claim For more information Open an issue in the Argo CD issue tracker or discussions Join us on Slack in channel #argo-cd Severity Critical 9.0/ 10 CVSS base metrics Attack vector Network Attack complexity High Privileges required None User interaction None Scope Changed Confidentiality High Integrity High Availability High CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H CVE ID CVE-2023-22482 Weaknesses No CWEs Credits @farcaller farcaller _____________________________________________________________________ Controller reconciles apps outside configured namespaces when sharding is enabled High crenshaw-dev published GHSA-6p4m-hw2h-6gmw Jan 25, 2023 Package github.com/argoproj/argo-cd (Go) Affected versions 2.5.0-rc1 through 2.5.7, 2.6.0-rc4 Patched versions 2.5.8, 2.6.0-rc5 Description Impact All Argo CD versions starting with 2.5.0-rc1 are vulnerable to an authorization bypass bug which allows a malicious Argo CD user to deploy Applications outside the configured allowed namespaces. Description of exploit Reconciled Application namespaces are specified as a comma-delimited list of glob patterns. When sharding is enabled on the Application controller, it does not enforce that list of patterns when reconciling Applications. For example, if Application namespaces are configured to be argocd-*, the Application controller may reconcile an Application installed in a namespace called other, even though it does not start with argocd-. Reconciliation of the out-of-bounds Application is only triggered when the Application is updated, so the attacker must be able to cause an update operation on the Application resource. Limitations This bug only applies to users who have explicitly enabled the "apps-in-any-namespace" feature by setting application.namespaces in the argocd-cmd-params-cm ConfigMap or otherwise setting the --application-namespaces flags on the Application controller and API server components. The apps-in-any-namespace feature is in beta as of this Security Advisory's publish date. The bug is also limited to Argo CD instances where sharding is enabled by increasing the replicas count for the Application controller. Finally, the AppProjects' sourceNamespaces field acts as a secondary check against this exploit. To cause reconciliation of an Application in an out-of-bounds namespace, an AppProject must be available which permits Applications in the out-of-bounds namespace. Patches A patch for this vulnerability has been released in the following Argo CD versions: v2.5.8 v2.6.0-rc5 Workarounds Running only one replica of the Application controller will prevent exploitation of this bug. Making sure all AppProjects' sourceNamespaces are restricted within the confines of the configured Application namespaces will also prevent exploitation of this bug. Credits Thanks to ChangZhuo Chen (@czchen) for finding the issue and for contributing the fix! References Documentation for apps-in-any-namespace For more information Open an issue in the Argo CD issue tracker or discussions Join us on Slack in channel #argo-cd Severity High 8.5/ 10 CVSS base metrics Attack vector Network Attack complexity High Privileges required Low User interaction None Scope Changed Confidentiality High Integrity High Availability High CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H CVE ID CVE-2023-22736 Weaknesses No CWEs Credits @czchen czchen @crenshaw-dev crenshaw-dev ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 23/25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email:cert@support.renater.fr + =========================================================