# CVE-2026-12583: Tribulant Newsletters PHP object injection in subscriber custom fields

Source: https://junglewise.ai/threats/cve-2026-12583-tribulant-newsletters-php-object-injection-in-subscriber-custom  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-12583 · Severity: info · CVSS 8.1 · Published 2026-07-14

The Newsletters plugin for WordPress, which manages email marketing and subscriber lists, contains a critical security flaw. An unauthenticated attacker can use a public subscription form to submit malicious data that, when processed by the server, allows them to create unauthorized files or execute arbitrary code. This could lead to a full takeover of the website, theft of subscriber data, or a complete service outage.

Technologies: [Tribulant Newsletters](https://junglewise.ai/threats/technologies/newsletters). Vendors: [Tribulant](https://junglewise.ai/threats/vendors/tribulant).

## Quick answers

**Is CVE-2026-12583 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12583 being exploited in the wild.

**How severe is CVE-2026-12583?** Informational severity, with a CVSS score of 8.1, published 14 July 2026.

**Which products and versions are affected?** Tribulant Newsletters < 4.15.

**Is there a fix for CVE-2026-12583?** A patch was published on 2026-07-14: Fixed in version 4.15 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-12583 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-12583?** Check whether you run Tribulant Newsletters at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The Newsletters plugin fails to properly validate or sanitize untrusted input stored through public subscription forms, leading to a PHP Object Injection vulnerability. An unauthenticated attacker can submit a serialized PHP object via a custom text field in the opt-in form. When the attacker later views a newsletter online using their subscriber ID and authkey, the plugin deserializes the stored field value. By utilizing a POP (Property-Oriented Programming) gadget chain present in the bundled GuzzleHttp library, an attacker can trigger a file-write primitive to create a web shell and achieve remote code execution. This issue is fixed in version 4.15.

## Affected products

- Tribulant Newsletters (newsletters-lite) < 4.15

## Timeline

- 2026-06-23: disclosed: Publicly published by WPScan
- 2026-07-14: advisory: NVD publication date
- 2026-07-14: patched: Fixed in version 4.15

## References

- [https://wpscan.com/vulnerability/e4c44105-f43d-4dff-8487-7d8ae2691c4e/](https://wpscan.com/vulnerability/e4c44105-f43d-4dff-8487-7d8ae2691c4e/)

## Related threats

- [WordPress Newsletters plugin SQL injection in wpmlsubscriber_id](https://junglewise.ai/threats/cve-2026-3018-wordpress-newsletters-plugin-sql-injection-in-wpmlsubscriber-id)