CVE-2026-66596

WordPress Newsletter plugin <= 9.3.3 - Cross Site Scripting (XSS) vulnerability

Unauthenticated Cross Site Scripting (XSS) in Newsletter <= 9.3.3 versions.

We have discovered 76,750 live websites that are affected by CVE-2026-66596.

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Affected Software

Product  Newsletter
Category Wordpress Plugins
Vulnerable Domains76,750 live websites (100% of Newsletter install base)
Vulnerable Versions
  • from 0 through 9.3.3
Vulnerable Versions Count399 versions ( 100% of all versions)


Common Weakness Enumeration

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



Details

  • Published - Aug 19, 2026
  • Updated - Aug 19, 2026

Credits

  • daroo | Patchstack Bug Bounty Program (finder)

Website Distribution by Country

Number of websites using CVE-2026-66596
United States17,741 websites


Germany14,300 websites
France6,067 websites
Italy5,631 websites
Poland2,996 websites
GB2,609 websites
Netherlands1,874 websites
Spain1,819 websites
Switzerland1,668 websites
Canada1,383 websites

Website Distribution by TLD

Number of websites using CVE-2026-66596
.com26,920 websites
.de9,393 websites
.org4,815 websites
.it4,005 websites
.fr2,710 websites
.pl2,157 websites
.net1,701 websites
.nl1,578 websites
.ch1,342 websites
.co.uk1,198 websites

Vulnerable Versions

Vulnerable versions are highlighted in red

Websites affected by CVE-2026-66596

Top websites that are affected by CVE-2026-66596. Please click on the "Contact us" link to get more information.
DomainCountryRankContacts
********.*********.com United States*,***
**********.com United States*,***
**********.com Germany*,***
*********.com United States*,***
***************.com United States**,***
****.***.br Brazil**,***
***************.pl Poland**,***
****************.com United States**,***
***********.org Germany**,***
**********.com United States**,***
See full domain list

FAQ

CVE-2026-66596 is Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in Newsletter
A total of 76,750 websites have been identified as vulnerable to CVE-2026-66596, based on global website indexing conducted by WebTechSurvey.
The Newsletter is affected by the CVE-2026-66596 vulnerability.
Newsletter versions up to and including 9.3.3 are vulnerable to CVE-2026-66596.