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CVE-2026-104083

6.1 · MEDIUM

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 nes…

Published Oct 9, 2026CWE-79EPSS 0.33%

Overview

CVE-2026-104083 is a medium-severity vulnerability. It was published on October 9, 2026 and has a CVSS 3.1 base score of 6.1 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.1, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refblog.evan.lat/posts/sm/Refwww.smartertools.com/smartermail/release-notes/current#/9526:~:text=Build%209777%20(Oct%208%2C%202026)Refwww.vulncheck.com/advisories/smartermail-build-9777-stored-mutation-xss-via-mathml-foreign-content

How CyberStrike helps

Frequently asked questions

What is CVE-2026-104083?

CVE-2026-104083 is a medium-severity vulnerability. It was published on October 9, 2026 and has a CVSS 3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-104083?

This vulnerability has a CVSS 3.1 base score of 6.1, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-104083?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-104083?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-104083 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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