CVE-2026-103482
The Simple Newsletter Plugin – Noptin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'noptin_fields[<custom_field_merge_tag>] (e.g. first_name)' parameter in all versions up to, and including, 4.3.10 due to insufficient input…
Does this matter?
Lower severity and a low EPSS score (0.31%). Track it; it rarely justifies an emergency change on its own.
Description
The Simple Newsletter Plugin – Noptin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'noptin_fields[<custom_field_merge_tag>] (e.g. first_name)' parameter in all versions up to, and including, 4.3.10 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The attack chain requires a published campaign post whose body contains a [[subscriber.*]] merge tag; the unauthenticated attacker first POSTs the entity-encoded payload to the public manage_preferences form (which issues its own nonce on the same page), then pivots execution by embedding their confirm_key in a campaign preview URL sent to a privileged user via social engineering.
- CVSS 3.1
- 5.4 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
- EPSS
- 0.31% probability · 24th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Source
- security@wordfence.com
EPSS moved from 0.3% on 10 October 2026 to 0.3% on 26 October 2026.
References
- https://github.com/hizzle-co/noptin/compare/4.3.10...4.4.0
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Core/Dynamic_Content_Tags.php#L361
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Core/Dynamic_Content_Tags.php#L507
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Core/Dynamic_Content_Tags.php#L695
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Emails/Generate/Generator.php#L548
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Emails/Preview.php#L161
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Subscribers/Manage_Preferences.php#L255
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/build/Subscribers/functions.php#L937
- https://plugins.trac.wordpress.org/browser/newsletter-optin-box/tags/4.3.10/vendor/hizzle/store/src/Prop.php#L626
- https://www.wordfence.com/threat-intel/vulnerabilities/id/e5f8afa3-f20c-4dfb-bcc6-2682f68723ca?source=cve
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.