Argo CD ServerSideDiff plaintext Kubernetes Secret disclosure
CVE-2026-42880 is a missing authorization and secret-masking flaw in Argo CD’s ServerSideDiff endpoint. In affected Argo CD versions 3.2.0 through before 3.2.11 and 3.3.0 through before 3.3.9, an authenticated attacker with read-only Argo CD application access can abuse the ServerSideDiff functionality to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server’s Server-Side Apply dry-run mechanism. The issue stems from insufficient authorization controls combined with a data-masking gap in the ServerSideDiff path, allowing secret values that should not be exposed to be returned in plaintext.
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Impact, mitigation & remediation
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Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a full lab and detection project for CVE-2026-42880 in Argo CD, centered on a Nuclei template but also containing a working local reproduction environment and a bash-based PoC. Because it is part of the Nuclei ecosystem, the main exploit artifact is nuclei/CVE-2026-42880.yaml, which performs a 4-step HTTP workflow: fingerprint Argo CD via GET /api/version, authenticate with POST /api/v1/session, enumerate applications with GET /api/v1/applications, and inspect GET /api/v1/applications/{app}/managed-resources for a Secret whose data fields are owned by a non-ArgoCD field manager. The template is condition-based detection rather than direct exploitation, since the actual vulnerable path is the gRPC ServerSideDiff handler and Nuclei cannot directly invoke that flow. The repository also includes operational bash scripts that build two Kind clusters: a vulnerable Argo CD v3.2.0 environment and a patched v3.2.11 comparison environment. scripts/01-setup-vuln.sh creates the vulnerable cluster, starts a Gitea container, pushes manifests, installs Argo CD, creates a read-only viewer account, deploys an Application with the required compare-options annotation, and injects Secret data using --server-side --field-manager=external-controller to create the field-manager split required for exploitation. scripts/02-setup-patched.sh mirrors the same setup against a patched version. scripts/03-trigger-cve.sh then uses argocd app diff --server-side-diff with a viewer token to exercise the real gRPC-backed vulnerable behavior and parse diff output for unmasked base64 Secret values. scripts/99-teardown.sh removes the lab. Repository structure is organized into documentation (README, setup guide, vulnerability analysis, English/Korean reports), Kubernetes manifests (Application, Argo CD config/RBAC patches, NodePort services), Kind cluster configs, a Git manifest containing Secrets without data fields, the Nuclei template, and automation scripts. Overall purpose: provide a reproducible research lab for CVE-2026-42880, demonstrate that low-privilege users can disclose Kubernetes Secrets through Argo CD ServerSideDiff when prerequisites are met, and supply a practical Nuclei detection template for identifying likely vulnerable deployments.
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Recent activity
12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An Argo CD vulnerability that allowed read-only users to read plaintext Kubernetes secrets.
A vulnerability in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data via the Kubernetes API server's Server-Side Apply dry-run mechanism.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.