Issuer not verified from obtained token in user_oidc

{
  "id": "34509dfc42c40335e77f91b0780eab3bda1347e86a81e7d7f21aa23cb4937215",
  "url": "https://osv.dev/vulnerability/CVE-2023-39953",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Issuer not verified from obtained token in user_oidc",
    "summary": "user_oidc provides the OIDC connect user backend for Nextcloud, an open-source cloud platform. Starting in version 1.0.0 and prior to version 1.3.3, missing verification of the issuer would have allowed an attacker to perform a man-in-the-middle attack returning corrupted or known token they also have access to. user_oidc 1.3.3 contains a patch. No known workarounds are available.",
    "evidence": "osv:CVE-2023-39953",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2023-39953",
      "aliases": [
        "CVE-2023-39953",
        "GHSA-xx3h-v363-q36j"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nextcloud/user_oidc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "2b27bd81899d8607f82ad41c2831bef91db835a5"
                },
                {
                  "fixed": "3ff24f81b96792d96a2647d7b1f857b891c84643"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "1.0.0"
                      },
                      {
                        "fixed": "1.3.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:nextcloud:user_oidc:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.0.0"
                      },
                      {
                        "fixed": "1.3.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.2.0",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.1",
            "v1.1.0",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-39953.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.480537635Z",
      "provider": "osv",
      "references": [
        "https://hackerone.com/reports/2021684",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/39xxx/CVE-2023-39953.json",
        "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-xx3h-v363-q36j",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-39953",
        "https://github.com/nextcloud/user_oidc/pull/642"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-303"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/39xxx/CVE-2023-39953.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-39953",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 495193,
  "published_at": "2023-08-10T13:55:19.957+00:00"
}