---
id: "CVE-2026-121621"
kind: "vulnerability"
aliases: ["CVE-2026-121621"]
title: "Argo CD Image Updater: proxy URL setting lets an attacker run shell commands"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "argocd-image-updater", "fixed": [], "affected": "unknown; fix merged in master after v1.4.0 (PR #1905)", "ecosystem": "vendor"}]
ecosystems: []
tags: ["argo-cd", "gitops", "infrastructure", "kubernetes"]
not_affected_if: ["no-ssh-git-proxy", "trusted-admins-only"]
published_at: "2026-11-03T21:17:37+00:00"
first_seen_at: "2026-11-03T21:19:30+00:00"
updated_at: "2026-11-03T21:22:26+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121621", "first_seen_at": "2026-11-03T21:19:30+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-03T21:22:26+00:00"}]
---

# Argo CD Image Updater: proxy URL setting lets an attacker run shell commands

Argo CD Image Updater passes a proxy URL from an SSH Git repository configuration unsanitized into a shell-interpreted SSH command. An attacker who can set a malicious proxy value can inject shell metacharacters to run arbitrary commands and read credentials held by the Image Updater process.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:argocd-image-updater affected unknown; fix merged in master after v1.4.0 (PR #1905) fixed ?

## How to check

Check which Argo CD Image Updater version you run (image tag of the argocd-image-updater deployment). No fixed release is confirmed yet: PR #1905 is merged in master and milestoned v1.5.0, so watch the releases page. Review repository and credential-template Secrets for SSH Git repositories that set a 'proxy' value, and remove any unexpected ones. Also check your Argo CD itself: the same flaw in Argo CD is fixed in 3.3.15, 3.4.10, 3.5.4 and 3.6.0-rc2.

## Fix

Fix merged to argocd-image-updater master in PR #1905 (2026-11-02, milestone v1.5.0); no released version confirmed yet. Until then, do not set a proxy on SSH Git repositories and limit who can edit repository config.

## Timeline

- 2026-11-03T21:19:30+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121621
- 2026-11-03T21:22:26+00:00 analyst — Red Hat page and merged PR #1905 (argocd-image-updater, merged 2026-11-02, milestone v1.5.0) confirm the flaw and fix in master. Same flaw as Argo CD CVE-2026-55797 / GHSA-j6cw-g6p4-7hch. No Image Updater advisory or release with the fix read; affected versions unknown. Image Updater releases through v1.4.0 and v1.3.2 do not mention it. Not verified.

## Documents

- [advisory] Red Hat CVE-2026-121621 https://access.redhat.com/security/cve/CVE-2026-121621
- [fix] fix: prevent command injection via SSH proxy handling in GIT_SSH_COMMAND (argocd-image-updater #1905) https://github.com/argoproj-labs/argocd-image-updater/pull/1905
- [mentions] Argo CD GHSA-j6cw-g6p4-7hch (CVE-2026-55797), same flaw in Argo CD https://github.com/argoproj/argo-cd/security/advisories/GHSA-j6cw-g6p4-7hch

## From the sources

A command injection vulnerability was found in Argo CD Image Updater, where a proxy URL configured on an SSH Git repository is passed unsanitized into a shell-interpreted SSH command. An attacker able to set a malicious proxy value can inject shell metacharacters to execute arbitrary commands and access credentials in the context of the Image Updater process.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_