CVE-2026-104083: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in Smartertools Smartermail
Description
SmarterMail before build 9777 contains a stored mutation cross-site scripting vulnerability that allows remote attackers to inject executable script by placing payloads inside a <style> element nested within MathML foreign content (<math><mtext><mglyph>), which the custom HTML sanitizer treats as inert CDATA text but browsers reparse as live markup. Attackers can deliver a crafted calendar (iCal) message containing an <img src=x onerror=...> payload that executes automatically in the recipient's webmail session at /interface/message-iframe when the message is opened, enabling script execution and data exfiltration unconstrained by the interface's permissive Content-Security-Policy.
CVSS v4.0
Score 5.3medium
Affected software
Smartertools
Smartermail
pkg:github/smartertools/smartermailRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-104083 is a stored cross-site scripting vulnerability in SmarterMail prior to build 9777. Attackers can embed malicious scripts inside a <style> element nested within MathML foreign content (<math><mtext><mglyph>), which the product's HTML sanitizer incorrectly treats as inert CDATA text. However, browsers reparse this content as live markup, enabling script execution. Exploitation can occur through a specially crafted calendar (iCal) message containing an <img src=x onerror=...> payload that triggers automatically when the message is opened in the webmail interface at /interface/message-iframe. This leads to script execution and data exfiltration, circumventing the interface's Content-Security-Policy restrictions.
Potential Impact
Successful exploitation allows remote attackers to execute arbitrary scripts in the context of the victim's webmail session, potentially leading to data theft or unauthorized actions within the application. The vulnerability bypasses the Content-Security-Policy, increasing the risk of impact.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-01T18:02:50.084Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ac9096e2cdf04f65664ff01
Added to database: 10/09/2026, 15:34:06 UTC
Last enriched: 10/09/2026, 15:48:53 UTC
Last updated: 10/09/2026, 22:44:39 UTC
Views: 15
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