Strategic Overview
- Status
- Patched in 4.6.8.6
- Affected Plugin
- Newsletters
- Affected Version
< 4.6.8.6- CVSS
- 9.8Critical
- Weakness type
- CWE-502 · Deserialization of Untrusted Data
- CVE
CVE-2018-20987
At a glance
CVE-2018-20987 is a critical-severity Deserialization of Untrusted Data vulnerability in the Newsletters WordPress plugin, affecting versions < 4.6.8.6. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 4.6.8.6; sites on affected versions should update now. Disclosed March 2018.
Vulnerability Overview
The newsletters-lite plugin before 4.6.8.6 for WordPress has PHP object injection.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.
CWE-502: Deserialization of Untrusted Data
Reaching this weakness in Newsletters < 4.6.8.6 takes a caller who can reach the endpoint. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.
A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For Newsletters the fix is 4.6.8.6: builds < 4.6.8.6 are affected, anything from 4.6.8.6 onward is not.
Remediation
Update to version 4.6.8.6, or a newer patched version
How does WordSec protect against this?
The attempt arrives as an ordinary request to Newsletters: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Newsletters 4.6.8.6 closes this, and updating the plugin is the step that ends it.
- Firewall
- Scanner
- Alerts
External References
Related records
Same weakness class
Other vulnerabilities in Newsletters
- 9.1CVE-2024-32954: Newsletters <= 4.9.5 Arbitrary File Upload
CVE-2024-32954 - 8.8CVE-2024-8247: Newsletters <= 4.9.9.2 Privilege Escalation
CVE-2024-8247 - 8.8CVE-2019-14788: Newsletters <= 4.6.18 Directory Traversal
CVE-2019-14788 - 8.1CVE-2025-54034: Newsletters <= 4.10 Local File Inclusion
CVE-2025-54034 - 7.5CVE-2026-3018: Newsletters <= 4.13 SQL Injection
CVE-2026-3018 - 7.2CVE-2026-16268: Newsletters <= 4.15 Server-Side Request Forgery
CVE-2026-16268 - 7.2CVE-2026-57394: Newsletters <= 4.14 Stored Cross-Site Scripting
CVE-2026-57394 - 7.2CVE-2025-4857: Newsletters <= 4.9.9.9 Local File Inclusion
CVE-2025-4857
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