Vulnerability-Lookup

GHSA-P4GQ-3VXJ-F4JQ

Vulnerability from github – Published: 2026-05-04 20:01 – Updated: 2026-05-13 13:39

Summary

Argo Affected by SSO RBAC Delegation Nil Pointer Dereference DoS (gatekeeper.go)

Details

Summary

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.

Details

When getServiceAccount(claims, ssoNamespace) returns nil (no matching rule), the error is suppressed and loginAccount remains nil. If RBAC delegation finds a matching namespaceAccount, line 304 calls precedence(loginAccount) which unconditionally accesses serviceAccount.Annotations — nil pointer dereference.

Affected code (v4.0.4):

// gatekeeper.go:304
} else if precedence(namespaceAccount) > precedence(loginAccount) {
    // loginAccount is nil here -> precedence(nil) -> PANIC

// gatekeeper.go:232-234
func precedence(serviceAccount *corev1.ServiceAccount) int {
    i, _ := strconv.Atoi(serviceAccount.Annotations[common.AnnotationKeyRBACRulePrecedence])
    return i
}

PoC

Live-tested 2026-04-17: kind cluster, Argo Workflows v4.0.4, Dex v2.43.1 OIDC provider.

Deploy Argo Workflows with --auth-mode=sso --auth-mode=client, SSO pointing to Dex, RBAC enabled.
Set SSO_DELEGATE_RBAC_TO_NAMESPACE=true on the argo-server deployment.
Create an RBAC ServiceAccount with workflows.argoproj.io/rbac-rule: "true" annotation in a target namespace (e.g., target-ns).
Do not create a matching RBAC rule in the SSO namespace (argo).
Authenticate via the Dex SSO flow.
Request GET /api/v1/workflows/target-ns with the SSO session cookie.
Server returns HTTP 500: {"code":13,"message":"runtime error: invalid memory address or nil pointer dereference"}
Server logs: Recovered from panic with stack trace at gatekeeper.go:233 (precedence()) called from gatekeeper.go:304.

Every subsequent API request from affected SSO users triggers the same panic.

Impact

Permanent denial of service for any SSO user whose claims don't match SSO-namespace RBAC but do match a target namespace rule. Realistic in multi-tenant deployments with per-namespace RBAC. The gRPC recovery interceptor catches the panic so the server process survives, but the affected user gets HTTP 500 on every request.

Suggested Fix

Add nil check: if loginAccount == nil || precedence(namespaceAccount) > precedence(loginAccount)

AI Disclosure

This advisory was prepared with AI assistance (Claude Code, Anthropic).

Severity

2.3 (Low)


                  
                    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

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JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.0.4"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/argoproj/argo-workflows/v4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42183"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-04T20:01:13Z",
    "nvd_published_at": "2026-05-09T04:16:23Z",
    "severity": "LOW"
  },
  "details": "### Summary\nA 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`.\n\n### Details\nWhen `getServiceAccount(claims, ssoNamespace)` returns nil (no matching rule), the error is suppressed and `loginAccount` remains nil. If RBAC delegation finds a matching `namespaceAccount`, line 304 calls `precedence(loginAccount)` which unconditionally accesses `serviceAccount.Annotations` \u2014 nil pointer dereference.\n\n**Affected code (v4.0.4):**\n\n```go\n// gatekeeper.go:304\n} else if precedence(namespaceAccount) \u003e precedence(loginAccount) {\n    // loginAccount is nil here -\u003e precedence(nil) -\u003e PANIC\n\n// gatekeeper.go:232-234\nfunc precedence(serviceAccount *corev1.ServiceAccount) int {\n    i, _ := strconv.Atoi(serviceAccount.Annotations[common.AnnotationKeyRBACRulePrecedence])\n    return i\n}\n```\n\n### PoC\n**Live-tested 2026-04-17:** kind cluster, Argo Workflows v4.0.4, Dex v2.43.1 OIDC provider.\n\n1. Deploy Argo Workflows with `--auth-mode=sso --auth-mode=client`, SSO pointing to Dex, RBAC enabled.\n2. Set `SSO_DELEGATE_RBAC_TO_NAMESPACE=true` on the argo-server deployment.\n3. Create an RBAC ServiceAccount with `workflows.argoproj.io/rbac-rule: \"true\"` annotation in a target namespace (e.g., `target-ns`).\n4. Do **not** create a matching RBAC rule in the SSO namespace (`argo`).\n5. Authenticate via the Dex SSO flow.\n6. Request `GET /api/v1/workflows/target-ns` with the SSO session cookie.\n7. Server returns HTTP 500: `{\"code\":13,\"message\":\"runtime error: invalid memory address or nil pointer dereference\"}`\n8. Server logs: `Recovered from panic` with stack trace at `gatekeeper.go:233` (`precedence()`) called from `gatekeeper.go:304`.\n\nEvery subsequent API request from affected SSO users triggers the same panic.\n\n### Impact\nPermanent denial of service for any SSO user whose claims don\u0027t match SSO-namespace RBAC but do match a target namespace rule. Realistic in multi-tenant deployments with per-namespace RBAC. The gRPC recovery interceptor catches the panic so the server process survives, but the affected user gets HTTP 500 on every request.\n\n### Suggested Fix\nAdd nil check: `if loginAccount == nil || precedence(namespaceAccount) \u003e precedence(loginAccount)`\n\n### AI Disclosure\nThis advisory was prepared with AI assistance (Claude Code, Anthropic).",
  "id": "GHSA-p4gq-3vxj-f4jq",
  "modified": "2026-05-13T13:39:11Z",
  "published": "2026-05-04T20:01:13Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/argoproj/argo-workflows/security/advisories/GHSA-p4gq-3vxj-f4jq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42183"
    },
    {
      "type": "WEB",
      "url": "https://github.com/argoproj/argo-workflows/commit/c4cc17d0c034fa9a9cc01ef1af6c8016c93071d4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/argoproj/argo-workflows"
    },
    {
      "type": "WEB",
      "url": "https://github.com/argoproj/argo-workflows/releases/tag/v4.0.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Argo Affected by SSO RBAC Delegation Nil Pointer Dereference DoS (gatekeeper.go)"
}

CVE-2026-42183 (GCVE-0-2026-42183)

Vulnerability from cvelistv5 – Published: 2026-05-09 03:44 – Updated: 2026-05-13 17:46

Title

Argo Workflows: SSO RBAC Delegation Nil Pointer Dereference DoS (gatekeeper.go)

Summary

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.

Severity

2.3 (Low)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-13 17:25 UTC

CWE

CWE-476 - NULL Pointer Dereference

Assigner

GitHub_M mitre root Scorecard

References

3 references

URL	Tags
https://github.com/argoproj/argo-workflows/securi…	x_refsource_CONFIRM
https://github.com/argoproj/argo-workflows/commit…	x_refsource_MISC
https://github.com/argoproj/argo-workflows/releas…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
argoproj	argo-workflows	Affected: >= 4.0.0, < 4.0.5

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42183",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-13T17:25:40.856061Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-13T17:46:04.800Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "argo-workflows",
          "vendor": "argoproj",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.0.5"
            }
          ]
        }
      ],
      "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": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.3,
            "baseSeverity": "LOW",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-476",
              "description": "CWE-476: NULL Pointer Dereference",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-09T03:44:10.712Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/argoproj/argo-workflows/security/advisories/GHSA-p4gq-3vxj-f4jq",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/argoproj/argo-workflows/security/advisories/GHSA-p4gq-3vxj-f4jq"
        },
        {
          "name": "https://github.com/argoproj/argo-workflows/commit/c4cc17d0c034fa9a9cc01ef1af6c8016c93071d4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/argoproj/argo-workflows/commit/c4cc17d0c034fa9a9cc01ef1af6c8016c93071d4"
        },
        {
          "name": "https://github.com/argoproj/argo-workflows/releases/tag/v4.0.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/argoproj/argo-workflows/releases/tag/v4.0.5"
        }
      ],
      "source": {
        "advisory": "GHSA-p4gq-3vxj-f4jq",
        "discovery": "UNKNOWN"
      },
      "title": "Argo Workflows: SSO RBAC Delegation Nil Pointer Dereference DoS (gatekeeper.go)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-42183",
    "datePublished": "2026-05-09T03:44:10.712Z",
    "dateReserved": "2026-04-25T01:53:21.582Z",
    "dateUpdated": "2026-05-13T17:46:04.800Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

GHSA-P4GQ-3VXJ-F4JQ

Summary

Details

PoC

Impact

Suggested Fix

AI Disclosure

CVE-2026-42183 (GCVE-0-2026-42183)

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