# Newsletters <= 4.18.2 - Unauthenticated PHP Object Injection via Date Custom Field

- **ID:** WPSEC-2026-2986
- **Plugin:** Newsletters (`newsletters-lite`), https://wordpress.org/plugins/newsletters-lite/
- **Affected versions:** all versions before 4.18.3
- **Fixed in:** 4.18.3 (Update to 4.18.3 or later.)
- **Severity:** High 8.1 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **Weakness:** CWE-502
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-11-12)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/newsletters-lite
- **Fix released:** 2026-11-10
- **Published:** 2026-11-12
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2986/

## Description

The Newsletters plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 4.18.2 via deserialization of untrusted input when rendering Date custom fields in the Bootstrap (default2) theme. Submitted request values, such as those posted to the front-end AJAX field refresh action, are passed to maybe_unserialize(). This makes it possible for unauthenticated attackers to inject a PHP object when a Date custom field is in use. No known POP chain is present in the plugin itself; if a POP chain is present via another plugin or theme installed on the target system, it may allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.

## References

- https://wpsec.com/vuln/WPSEC-2026-2986/
- https://plugins.svn.wordpress.org/newsletters-lite/tags/4.18.3/
- https://wordpress.org/plugins/newsletters-lite/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2986/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.