{"id":"GHSA-qj6w-v29q-4rgx","aliases":["CVE-2026-39960"],"title":"MantisBT is Vulnerable to Stored XSS in Custom Field Textarea Values","titleSource":"OSV","descriptionSource":"OSV","declaredSeverity":"MODERATE","description":"Improper escaping of a textarea custom field's contents in the Update Issue page (bug_update_page.php) allows an attacker to inject HTML and, if CSP settings permit, execute arbitrary JavaScript when the page is loaded.\n\n### Impact\nSession theft leading to admin account takeover, full project data access.\n\n- Precondition: A textarea-type custom field must be configured for the project\n- Attacker: Authenticated user with bug report permission (low privilege)\n- Victim: Any user viewing the bug edit form, including administrators\n\n### Patches\n- 5fec0f448b7a7d7d539a6adb6dccceac4e4e4ab7\n\n### Workarounds\nThe default Content-Security Policy will block script execution.\n\n### References\n- https://mantisbt.org/bugs/view.php?id=37003\n- This is related to [CVE-2024-34081](https://github.com/advisories/GHSA-wgx7-jp56-65mq).\n\n### Credits\nThanks to the following security researchers for independently discovering and responsibly reporting the issue, and providing a patch to fix it.\n- Thanks to Nozomu Sasaki (Paul) (@morimori-dev)\n- Tristan Madani (@TristanInSec) from Talence Security","severity":"medium","score":5.4,"published":"2026-05-11T19:34:32.000Z","modified":"2026-09-10T03:51:06.801Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"mantisbt/mantisbt","sources":[{"name":"OSV · GHSA-qj6w-v29q-4rgx","url":"https://osv.dev/vulnerability/GHSA-qj6w-v29q-4rgx"}],"ranges":[{"events":[{"introduced":"0"},{"fixed":"2.28.2"}],"type":"ECOSYSTEM"}],"versions":["2.10.0","2.10.1","2.11.0","2.11.1","2.12.0","2.12.1","2.12.2","2.13.0","2.13.1","2.13.2","2.14.0","2.15.0","2.15.1","2.16.0","2.16.1","2.17.0","2.17.1","2.17.2","2.18.0","2.18.1","2.19.0","2.19.1","2.20.0","2.20.1","2.21.0","2.21.1","2.21.2","2.21.3","2.22.0","2.22.1","2.22.2","2.23.0","2.23.1","2.24.0","2.24.1","2.24.2","2.24.3","2.24.4","2.24.5","2.25.0","2.25.1","2.25.2","2.25.3","2.25.4","2.25.5","2.25.6","2.25.7","2.25.8","2.26.0","2.26.1","2.26.2","2.26.3","2.26.4","2.27.0","2.27.1","2.27.2","2.27.3","2.28.0","2.28.1","2.3.0","2.3.1","2.3.2","2.3.3","2.4.0","2.4.1","2.4.2","2.5.0","2.5.1","2.5.2","2.6.0","2.7.0","2.7.1","2.8.0","2.8.1","2.9.0","2.9.1"],"fixed":["2.28.2"]}],"sourceAffected":[],"references":["https://github.com/mantisbt/mantisbt/security/advisories/GHSA-qj6w-v29q-4rgx","https://nvd.nist.gov/vuln/detail/CVE-2026-39960","https://github.com/mantisbt/mantisbt/commit/5fec0f448b7a7d7d539a6adb6dccceac4e4e4ab7","https://github.com/mantisbt/mantisbt","https://mantisbt.org/bugs/view.php?id=37003"],"sources":[{"name":"OSV","id":"GHSA-qj6w-v29q-4rgx","modified":"2026-09-10T03:51:06.801643399Z","url":"https://osv.dev/vulnerability/GHSA-qj6w-v29q-4rgx"}],"assessments":[{"source":"OSV","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","score":5.4}],"products":[],"remediation":[],"kev":{"status":"not-listed","checkedAt":"2026-10-29T01:50:33.295Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}