{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "1.18.4"
              },
              {
                "last_affected": "1.18.4"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "3320c4140371b62d8694eeaf943e606d902f007a"
            },
            {
              "last_affected": "3320c4140371b62d8694eeaf943e606d902f007a"
            }
          ],
          "repo": "https://github.com/humhub/humhub",
          "type": "GIT"
        }
      ],
      "versions": [
        "1.18.4"
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Fluid Attacks",
    "cwe_ids": [
      "CWE-79"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18756.json"
  },
  "details": "HumHub Community Edition 1.18.4 contains a reflected cross-site scripting vulnerability in the Space membership-request workflow. An attacker can place attacker-controlled button configuration in the options query-string parameter of space/membership/request-membership-form, lure an authenticated non-member into submitting the legitimate membership request form, and cause the server to return JavaScript containing attacker-controlled code.",
  "id": "CVE-2026-18756",
  "modified": "2026-08-30T03:31:05.941835717Z",
  "published": "2026-08-19T14:46:25.019Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://fluidattacks.com/es/advisories/turizo"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18756.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18756"
    },
    {
      "type": "FIX",
      "url": "https://github.com/humhub/humhub/pull/8381"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/humhub/humhub"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "HumHub Community Edition 1.18.4-pl1 - Reflected XSS in Space membership request button rendering"
}