Path traversal allows leaking out-of-bound files from Argo CD repo-server

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Argo CD starting with version 1.5.0 but before versions 2.1.11, 2.2.6, and 2.3.0 is vulnerable to a path traversal vulnerability, allowing a malicious user with read/write access to leak sensitive files from Argo CD's repo-server. A malicious Argo CD user who has been granted create or update access to Applications can leak the contents of any text file on the repo-server. By crafting a malicious Helm chart and using it in an Application, the attacker can retrieve the sensitive file's contents either as part of the generated manifests or in an error message. The attacker would have to know or guess the location of the target file. Sensitive files which could be leaked include files from another Application's source repositories or any secrets which have been mounted as files on the repo-server. This vulnerability is patched in Argo CD versions 2.1.11, 2.2.6, and 2.3.0. The problem can be mitigated by avoiding storing secrets in git, avoiding mounting secrets as files on the repo-server, avoiding decrypting secrets into files on the repo-server, and carefully limiting who can create or update Applications.