{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "4.15.3"
              },
              {
                "fixed": "4.17.3"
              }
            ]
          },
          "events": [
            {
              "introduced": "7ad3a61e84c0266d24e34d8ce3ebd13154d60b92"
            },
            {
              "fixed": "17bf79c1dbc249b6c79d585eba1414838dc43521"
            }
          ],
          "repo": "https://github.com/craftcms/cms",
          "type": "GIT"
        },
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "5.7.5"
              },
              {
                "fixed": "5.9.7"
              }
            ]
          },
          "events": [
            {
              "introduced": "679b82edce8c60ce1008dc70740bf2610adac57d"
            },
            {
              "fixed": "9986382fbf26ed5cd46926ecd84084bf1b564680"
            }
          ],
          "repo": "https://github.com/craftcms/cms",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-fvwq-45qv-xvhv"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-116",
      "CWE-79"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31859.json"
  },
  "details": "Craft is a content management system (CMS). The fix for CVE-2025-35939 in craftcms/cms introduced a strip_tags() call in src/web/User.php to sanitize return URLs before they are stored in the session. However, strip_tags() only removes HTML tags (angle brackets) -- it does not inspect or filter URL schemes. Payloads like javascript:alert(document.cookie) contain no HTML tags and pass through strip_tags() completely unmodified, enabling reflected XSS when the return URL is rendered in an href attribute. This vulnerability is fixed in  5.9.7 and 4.17.3.",
  "id": "CVE-2026-31859",
  "modified": "2026-04-01T23:08:08.675516825Z",
  "published": "2026-03-11T17:37:19.065Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31859.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31859"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Craft has Reflective XSS via incomplete return URL sanitization"
}