CVE-2026-104083 json
SmarterMail < Build 9777 Stored Mutation XSS via MathML Foreign Content
published 2026-10-09 31 d ago modified 2026-10-27 13 d ago also EUVD-2026-95888
- cvss
- 6.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 25%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- Smartertools Smartermail Build 9777
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 27 d ago
Exploit prediction
0.33% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- blog.evan.lat https://blog.evan.lat/posts/sm/ referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 5.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N |
| CNA | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| CNA | 4.0 | 5.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected products
- Smartertools Smartermail
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
smartertools.com
/smartermail/release-notes/current#/9526:~:text=Build%209777%20(Oct%208%2C%202026)
release-notes, patch
-
blog.evan.lat
/posts/sm/
technical-description, exploit
-
vulncheck.com
/advisories/smartermail-build-9777-stored-mutation-xss-via-mathml-foreign-content
third-party-advisory
Sources
- CVE List CVE-2026-104083
- NVD CVE-2026-104083
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