Argo CD Fixes High-Severity Command Injection in SSH Proxy Handling

Argo CD has released patches for a high-severity command injection vulnerability in its repo-server component. The flaw, tracked as CVE-2026-55797, allows attackers to execute arbitrary shell commands by supplying crafted proxy hostnames when configuring SSH Git repositories.

The vulnerability exists because the repo-server embeds the proxy host and port directly into an SSH `ProxyCommand` without neutralizing shell metacharacters. When the server clones, tests, or fetches from an SSH repository configured with a proxy URL, it executes this command through a shell. An attacker who can create or update a repository or a repository credential template can inject malicious commands that break out of the intended structure. This execution occurs within the context of the repo-server process, potentially allowing the attacker to access other Git, Helm, and OCI credentials stored for that service.

Context and Background

The issue was introduced in January 2024 with commit 9b27aeb1a4, which added SOCKS5 proxy support for SSH Git URLs. This feature was first released in Argo CD version 2.11.0. According to the GitHub advisory, the vulnerability affects all versions from 2.11.0 onward, including every currently supported release. Versions 2.10.20 and earlier are not affected because they lack this specific proxy handling logic.

The vulnerability applies specifically to SSH repositories. While HTTP, HTTPS, and SOCKS5 proxy URLs can be set on an SSH repository, they all trigger the vulnerable code path. However, HTTPS Git repositories use the proxy as a standard HTTP proxy and do not build the shell command in question, making them immune to this specific injection vector.

Who Is Affected

Users of Argo CD versions 2.11.0 through 2.14.21, 3.0.0 through 3.3.14, 3.4.0 through 3.4.9, 3.5.0 through 3.5.3, and 3.6.0-rc1 are vulnerable. The National Vulnerability Database rates the severity as High with a CVSS score of 8.8, citing CWE-78 (Improper Neutralization of Special Elements used in an OS Command).

Patches have been released for the following versions: 3.3.15, 3.4.10, 3.5.4, and 3.6.0-rc2. The fix stops passing the proxy host and port through a shell. Argo CD versions 2.x and 3.0 through 3.2 are out of support and will not receive a patch. Users on these unsupported lines are advised to upgrade to a patched 3.3 or newer release.

What should you do?

Administrators should verify their current Argo CD version and upgrade to the latest patched release immediately if they are within the affected range. Since there is no configuration setting that retains SSH repository proxies while removing the shell command, upgrading is the primary mitigation. Organizations should also review access controls to ensure that only trusted users have permissions to create or update repositories and credential templates.