Threat intelligence

MailOptin – Popup, Optin Forms & Email Newsletters for Mailchimp, HubSpot, AWeber Etc. <= 1.2.78.0 - Authenticated (Contributor+) Stored Cross-Site Scripting

CVE-2026-66703 · mailoptin

Important: Seeing this vulnerability listed does not mean your website is affected. Exposure depends on whether you run Mailoptin at a vulnerable version. How SiteRespond intelligence works

Vulnerability: MailOptin – Popup, Optin Forms & Email Newsletters for Mailchimp, HubSpot, AWeber Etc. <= 1.2.78.0 - Authenticated (Contributor+) Stored Cross-Site Scripting
Affected software: mailoptin(Plugin)
Affected versions: ≤ 1.2.78.0
Authentication: Authenticated (see advisory title)
Vulnerability type: Cross-site scripting
CVE: CVE-2026-66703
Published: 29 July 2026
CISA KEV: Not listed in CISA KEV at last catalog refresh
Impact: May allow attackers to run scripts in visitors' browsers or hijack admin sessions.
Source: Data imported from Wordfence Intelligence (advisory 277b8437-a215-445c-8257-b0ca3f36336d). Methodology and redistribution notes

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