Cross-Site Scripting (XSS) in mantisbt/mantisbt (CVE-2026-39960)
Summary
Cross-site scripting in mantisbt/mantisbt (CVE-2026-39960). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 2.28.2 or later.
Original description
The description as published by the source.
Mantis Bug Tracker (MantisBT) is an open source issue tracker. Versions 2.28.1 and below contain flawed logic that causes improper escaping of a textarea custom field's contents in the Update Issue page, (bug_update_page.php) allowing an attacker to inject HTML and, if CSP settings permit, execute arbitrary JavaScript when the page is loaded. This facilitates session theft, leading to admin account takeover, full project data access. In order to exploit this issue, a textarea-type custom field must be configured for the project, the attack must be carried out by an authenticated user with bug report permission (low privilege). This can affect any user viewing the bug edit form, including administrators. The issue has been fixed in version 2.28.2. If users cannot immediately upgrade, they can work around the issue by using the default Content-Security Policy, which blocks script execution.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-39960 has been found in mantisbt/mantisbt.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade mantisbt/mantisbt to 2.28.2 or later.
If unsure, ask your IT team or search "mantisbt/mantisbt CVE-2026-39960" on the vendor's site.
CVE-2026-39960 (mantisbt/mantisbt) — CWE-79 / CVSS v3 5.4
Attack vector: remote (network-reachable)
Patched: 2.28.2 — apply immediately
Workaround: The default Content-Security Policy will block script execution.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in mantisbt/mantisbt.
Check the vendor advisory for the affected versions of mantisbt/mantisbt.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 2.28.2.
Workaround: The default Content-Security Policy will block script execution.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'mantisbt/mantisbt' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'mantisbt/mantisbt' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
mantisbt/mantisbtを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
The default Content-Security Policy will block script execution.パッチが適用されるまでの応急処置として、The default Content-Security Policy will block script execution. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply patch patch
Upgrade mantisbt/mantisbt to 2.28.2ステージング環境で 2.28.2 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- web mantisbt.org
- web github.com