OpenProject: Stored XSS on openproject.example.com through /api/v3/projects/{project}/work_packages via POST parameter "description"

{
  "id": "7f262c82acdf91de2fbaf7d1f4a5ad1d723d431402d197e15858b27900dfe7d5",
  "url": "https://osv.dev/vulnerability/CVE-2026-52781",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "OpenProject: Stored XSS on openproject.example.com through /api/v3/projects/{project}/work_packages via POST parameter \"description\"",
    "summary": "OpenProject is open-source, web-based project management software. Prior to 17.3.3 and 17.4.1, the HTML sanitizer grants elements unrestricted data-* attributes via :data wildcard. An attacker injects data-controller=\"poll-for-changes\" into a work package description, causing Stimulus.js to mount a controller that fetches an attacker-uploaded attachment and passes it to renderStreamMessage(). This executes arbitrary Turbo Stream actions — including redirect_to — in every victim's authenticated browser session, redirecting them to an attacker-controlled server. This vulnerability is fixed in 17.3.3 and 17.4.1.",
    "evidence": "osv:CVE-2026-52781",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-52781",
      "aliases": [
        "CVE-2026-52781",
        "GHSA-q33w-f822-hg8x"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/opf/openproject",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5ee515c5c80c3aaf1e7527f63e4e69798aef1b29"
                },
                {
                  "introduced": "57fb3abf08b0075149e7abe7dbf5de99e07aee06"
                },
                {
                  "fixed": "8203fc2286fd48d7d72f52b3c4a2487f96fcea28"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "17.3.3"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "17.4.0"
                      },
                      {
                        "fixed": "17.4.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v17.3.1",
            "v17.4.0",
            "v17.3.2",
            "11.2.1",
            "v10.5",
            "v9.0.0-pre",
            "v5.0.4",
            "sprint/2015_04",
            "sprint/2015_03",
            "sprint/2015_02",
            "sprint/2015_01",
            "sprint/2014_18",
            "sprint/2014_16",
            "sprint/2014_13",
            "sprint/2014_12",
            "sprint/2014_11",
            "sprint/2014_10",
            "sprint/2014_09",
            "sprint/2014_08",
            "2.4.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52781.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:52.484438369Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52781.json",
        "https://github.com/opf/openproject/security/advisories/GHSA-q33w-f822-hg8x",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-52781"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52781.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-52781",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 521403,
  "published_at": "2026-06-26T19:00:10.717+00:00"
}