CVE-2026-44657: MantisBT Vulnerable to Stored XSS in File Download

Using *show_inline=1parameter and a valid *file_show_inline_tokenCSRF token on file_download.php, an attacker can execute code by uploading a crafted XHTML attachment referencing a JavaScript attachment. Impact Cross-si…

7.5CVSS Score

HIGHSeverity

NOCISA KEV

VulnerabilityImpact Type

📋 Vulnerability Details

CVE ID	CVE-2026-44657
Vendor	composer
Affected Product	mantisbt/mantisbt
Vulnerability Type	Vulnerability
CVSS Score	7.5 (HIGH)
Actively Exploited	❌ No known exploitation
Patch Status	See Vendor Advisory →
Reported By	CYBERDUDEBIVASH SENTINEL APEX Intelligence (via github_advisories)

🔬 Technical Analysis

Using *show_inline=1* parameter and a valid *file_show_inline_token* CSRF token on file_download.php, an attacker can execute code by uploading a crafted XHTML attachment referencing a JavaScript attachment.

Impact

Cross-site scripting

Patches

• 26647b2e68ba30b9d7987d4e03d7a16416684bc2

Workarounds

None

Credits

Thanks to siunam (Tang Cheuk Hei) for discovering and responsibly reporting the issue.

🎯 Known Indicators of Compromise

{"type":"sha1","value":"26647b2e68ba30b9d7987d4e03d7a16416684bc2","confidence_score":0.9,"first_seen":"2026-05-11","source_count":1}

📚 Advisory References

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