CVE-2026-66606Network attack vector

Unauthenticated stored XSS via mail log viewer

Published Aug 20, 2026 · Updated Aug 20, 2026

Cross-site scripting in ThemeGrill SmartSMTP 1.2.0 and earlier allows remote attackers to execute script in the mail log viewer via crafted email content. The vulnerable mail logs viewer renders attacker-controlled HTML from logged email content, and the 1.2.1 changelog shows the fix added server-side sanitization and sandboxed iframe rendering. Exploitation requires a path to place HTML into a logged message and an administrator or other privileged user to open the affected log entry, so the result is script execution in that browser context.

CVSS severity7.1
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in ThemeGrill SmartSMTP 1.2.0 and earlier allows remote attackers to execute script in the mail log viewer via crafted email content. The vulnerable mail logs viewer renders attacker-controlled HTML from logged email content, and the 1.2.1 changelog shows the fix added server-side sanitization and sandboxed iframe rendering. Exploitation requires a path to place HTML into a logged message and an administrator or other privileged user to open the affected log entry, so the result is script execution in that browser context.

The record

CVE
CVE-2026-66606
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
ThemeGrill
Product
SmartSMTP
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a <=1.2.0 changes=[{"at":"1.2.1","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ThemeGrill · SmartSMTPversion=n/a <=1.2.0 changes=[{"at":"1.2.1","status":"unaffected"}]

Published CVSS scores

7.1PatchstackCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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