What's New in Argo CD v3.5.4: Critical Security Patch Release

💡 Quick Answer: Argo CD v3.5.4 is a critical security patch release fixing four CRITICAL and two HIGH severity vulnerabilities in the repo-server (Kustomize remote refs, Kustomize Helm config home, Jsonnet imports, and AppProject hook bypass), plus a login rate-limit bypass and SSH proxy command injection. Upgrade immediately via kubectl apply --server-side or Helm.

The Problem

Argo CD v3.5.4 addresses a cluster of security advisories affecting any instance that evaluates untrusted or semi-trusted Git/Helm/OCI sources through the repo-server. Several of these are remote-code-execution or arbitrary file-read issues reachable by anyone who can push an Application manifest, Kustomize overlay, or Jsonnet file into a tracked repo — a realistic threat model for multi-tenant GitOps setups.

The Solution

Upgrade to v3.5.4. There are no new user-facing features beyond a login-attempt logging improvement; this release exists almost entirely to ship the coordinated security fix (#30038) and a handful of cherry-picked bug fixes from the 3.5 branch.

What’s New

Security fixes (upgrade priority: immediate)

• CRITICAL — Kustomize remote ref can run commands in the repo-server (GHSA-9v9p-x54c-58gc)
• CRITICAL — Kustomize Helm configHome can run commands in the repo-server (GHSA-fw5c-w8rc-j7fx)
• CRITICAL — Jsonnet import can read files from the repo-server (GHSA-m3vr-7329-44ww)
• CRITICAL — AppProject restrictions bypassed via PreDelete/PostDelete resource hooks (GHSA-fmxq-cgp8-87wp, CVE-2026-77459)
• HIGH — Login failure rate limit bypassable via concurrent requests (GHSA-4439-h7jw-5cjj, CVE-2025-61560)
• HIGH — Command injection via repository proxy URL on SSH Git repos (GHSA-j6cw-g6p4-7hch, CVE-2026-55797)
• MODERATE — Extension proxy RBAC ignores application namespace when applications-in-any-namespace is enabled (GHSA-g3ff-q88g-chrj)
• MODERATE — Oversized OCI manifest can exhaust repo-server memory (GHSA-w996-f2wq-x9c6)

Breaking changes

• Kustomize builds that render Helm charts no longer honor helmGlobals.configHome. Ordinary http, https, and oci chart repos still work, but builds relying on a Helm plugin registered from that directory will break.
• OCI manifests larger than 4 MiB are now rejected outright.

Other notable changes

• feat(server): username is now logged on login attempts (#29861) — useful for audit trails.
• fix(cmp): clean up tgz stream temp directories, preventing disk-space leaks (#29148/#29773).
• fix(ui): manifest viewer jumpiness resolved (#29691/#29725).
• fix(repo-server): health check timeout no longer causes CrashLoopBackOff (#29901).

No feature/deprecation changelog beyond the above was published for 3.5.4 — check the release page and the v3.0 release blog post for broader architectural context if you’re coming from a pre-3.x install.

Upgrade Steps

Option 1: kubectl (non-HA)

kubectl create namespace argocd
kubectl apply -n argocd --server-side --force-conflicts \
  -f https://raw.githubusercontent.com/argoproj/argo-cd/v3.5.4/manifests/install.yaml

Option 2: kubectl (HA)

kubectl create namespace argocd
kubectl apply -n argocd --server-side --force-conflicts \
  -f https://raw.githubusercontent.com/argoproj/argo-cd/v3.5.4/manifests/ha/install.yaml

Option 3: Helm

helm repo add argo https://argoproj.github.io/argo-helm
helm repo update
helm upgrade --install argocd argo/argo-cd \
  --namespace argocd --create-namespace \
  --set global.image.tag=v3.5.4

If you are jumping across minor versions, read the upgrade overview first.

Verify container image signatures (optional but recommended for this security release)

cosign verify \
  --certificate-identity-regexp 'https://github.com/argoproj/argo-cd/.*' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  quay.io/argoproj/argocd:v3.5.4

Verify

# Confirm rollout and version
kubectl -n argocd rollout status deploy/argocd-server
kubectl -n argocd exec deploy/argocd-server -- argocd version --short

# Confirm repo-server picked up the new image
kubectl -n argocd get pods -l app.kubernetes.io/name=argocd-repo-server \
  -o jsonpath='{.items[*].spec.containers[*].image}'

# Spot-check that AppProject hook restrictions are enforced (no PreDelete/PostDelete bypass)
kubectl -n argocd logs deploy/argocd-server --since=10m | grep -i 'login attempt'

Common Issues

• Kustomize+Helm build fails after upgrade: if a build previously relied on helmGlobals.configHome pointing at a custom Helm plugin directory, it will now fail. Migrate to a standard http/https/oci chart repo reference instead.
• OCI image/manifest sync errors: Applications pulling OCI artifacts larger than 4 MiB will start failing sync with a size-limit error — this is the new hard cap from GHSA-w996-f2wq-x9c6, not a bug.
• CrashLoopBackOff on repo-server before this release: fixed by #29901; if you still see it after upgrading, check for unrelated resource limits.

Best Practices

• Treat this as a mandatory, not optional, upgrade — four CRITICAL advisories affect the repo-server’s handling of untrusted repo content.
• After upgrading, review AppProject configs that use PreDelete/PostDelete resource hooks to confirm they are now correctly scoped.
• Enable and monitor the new login-attempt username logging for brute-force/credential-stuffing detection.
• Verify image provenance/signatures with cosign for any security-driven patch release before rolling to production.
• Pin the exact patch tag (v3.5.4) in GitOps manifests/Helm values rather than tracking a floating minor tag, so security patches are applied deliberately.