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.
CVE-2026-39960
This medium-severity CVE scores 5.4 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 86% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.4
- EG Score
- 5.4(medium)
- EG Risk
- 24(Track)EG Risk 24/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity54% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 14%
- KEV
- Not listed
Published
May 20, 2026
Last Modified
July 23, 2026
Advisory Details (2)
Auto-updated Jun 16, 2026Stored XSS in Custom Field Textarea Values · Advisory · mantisbt/mantisbt · GitHub
https://github.com/mantisbt/mantisbt/security/advisories/GHSA-qj6w-v29q-4rgxcommit 5fec0f448b7a (mantisbt/mantisbt)
Fix landed in mantisbt/mantisbt commit 5fec0f448b7a — awaiting tagged release
https://github.com/mantisbt/mantisbt/commit/5fec0f448b7a7d7d539a6adb6dccceac4e4e4ab7Vendor Advisories for CVE-2026-39960(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
Packagist(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| mantisbt/mantisbt | 2.10.0 ... 2.9.1 (76 versions) | 2.28.2 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 13× in last 7d / 48× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 127 total refreshes for this CVE.
- 2026-08-15 01:30 UTCEPSS rescore
- 2026-08-14 12:15 UTCEG score recompute
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- 2026-08-01 04:16 UTCEPSS rescore
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Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-39960?
When was CVE-2026-39960 disclosed?
Is CVE-2026-39960 actively exploited?
What is the CVSS score of CVE-2026-39960?
How do I remediate CVE-2026-39960?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-39960
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