Actual has an OpenID `client_secret` Disclosure via Broken Authorization Guard in `/openid/config`

{
  "id": "34ad005318df27dfe58d199dc97350e2eb4b336a64f87fa2b68279c1992c7210",
  "url": "https://osv.dev/vulnerability/CVE-2026-42604",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Actual has an OpenID `client_secret` Disclosure via Broken Authorization Guard in `/openid/config`",
    "summary": "Actual is a local-first personal finance tool. The `POST /openid/config` endpoint in Actual Budget's sync-server versions <= 26.4.0 exposes the full OpenID Connect configuration—including the OAuth2 `client_secret`—to any caller who knows the bootstrap password. The endpoint also lacks authentication and rate limiting, making the bootstrap password brute-forceable. Version 26.5.0 fixes the issue.",
    "evidence": "osv:CVE-2026-42604",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-42604",
      "aliases": [
        "CVE-2026-42604",
        "GHSA-49v6-pqjq-xw55"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/actualbudget/actual",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4c62e2a75d48deb06d45e7ed89a2b9ddfd187e3d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "26.5.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "26.4.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v26.4.0",
            "v26.3.0",
            "v26.2.0",
            "v26.1.0",
            "v25.12.0",
            "v25.11.0",
            "v25.10.0",
            "v25.9.0",
            "v25.8.0",
            "v25.7.1",
            "v25.7.0",
            "v25.6.1",
            "v25.6.0",
            "v25.5.0",
            "v25.4.0",
            "v25.3.0",
            "v25.2.0",
            "v25.1.0",
            "v24.12.0",
            "v24.11.0",
            "v24.10.0",
            "v24.9.0",
            "v24.8.0",
            "v24.7.0",
            "v24.6.0",
            "v24.5.0",
            "v24.4.0",
            "v24.3.0",
            "v24.2.0",
            "v24.1.0",
            "v23.12.0",
            "v23.11.0",
            "v23.10.0",
            "v23.9.0",
            "v23.8.1",
            "v23.8.0",
            "v23.7.2",
            "v23.7.1",
            "v23.7.0",
            "v23.6.0",
            "v23.5.0",
            "v23.4.2",
            "v23.4.1",
            "v23.4.0",
            "v23.3.2",
            "v23.3.0",
            "v23.2.9",
            "v23.2.5",
            "v23.1.12",
            "v22.12.9"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42604.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.151688663Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42604.json",
        "https://github.com/actualbudget/actual/security/advisories/GHSA-49v6-pqjq-xw55",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42604",
        "https://actualbudget.org/blog/release-26.5.0"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-863"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42604.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42604",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518418,
  "published_at": "2026-06-12T18:42:38.346+00:00"
}