Security advisory

{
  "id": "8bf203c4fc13ec9fbf71e917b47e5cc83098d8c08bf6907065f9aedc3cf5dc4a",
  "url": "https://osv.dev/vulnerability/CVE-2025-27556",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2025-27556",
    "summary": "An issue was discovered in Django 5.1 before 5.1.8 and 5.0 before 5.0.14. The NFKC normalization is slow on Windows. As a consequence, django.contrib.auth.views.LoginView, django.contrib.auth.views.LogoutView, and django.views.i18n.set_language are subject to a potential denial-of-service attack via certain inputs with a very large number of Unicode characters.",
    "evidence": "osv:CVE-2025-27556",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-27556",
      "aliases": [
        "BIT-django-2025-27556",
        "CVE-2025-27556",
        "GHSA-wqfg-m96j-85vm",
        "PYSEC-2025-14"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/django/django",
              "type": "GIT",
              "events": [
                {
                  "introduced": "52821001bb62b764d73e63812133f199b8fef9eb"
                },
                {
                  "fixed": "7c128112a6adff20b6d67a02c4098a2c10f88191"
                },
                {
                  "introduced": "84d09a547fe35e10018ab242602ca76c29ca91a1"
                },
                {
                  "fixed": "5773bc9cf929f4648da30cb9c472b816bb4db771"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:djangoproject:django:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.0"
                      },
                      {
                        "fixed": "5.0.14"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:djangoproject:django:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.1"
                      },
                      {
                        "fixed": "5.1.8"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-27556.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.693924873Z",
      "provider": "osv",
      "references": [
        "https://docs.djangoproject.com/en/dev/releases/security/",
        "https://groups.google.com/g/django-announce",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/27xxx/CVE-2025-27556.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-27556",
        "https://www.djangoproject.com/weblog/2025/apr/02/security-releases/"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "cna_assigner": "mitre",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "5.0"
                  },
                  {
                    "fixed": "5.0.14"
                  },
                  {
                    "introduced": "5.1"
                  },
                  {
                    "fixed": "5.1.8"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/27xxx/CVE-2025-27556.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-27556",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513879,
  "published_at": "2025-04-02T00:00:00+00:00"
}