Improperly implemented security check for standard in MantisBT - CVE-2026-40597
Published: November 6, 2026
Vulnerability identifier: #VU159800
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-40597
CWE-ID: CWE-358
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a low-privileged remote attacker to bypass MantisBT's Content Security Policy and execute JavaScript through a pre-existing XSS or HTML injection vulnerability.
The vulnerability exists due to crafted issue attachments being served through file_download.php with a valid JavaScript MIME type that satisfies the policy's script-source restrictions. A low-privileged remote attacker can upload such an attachment and reference it through the existing injection vulnerability to execute scripts in a victim's browser.
Affected software
MantisBT
How to mitigate CVE-2026-40597
Install security update from vendor's website.
MantisBT - update to 2.28.2