Improper Input Validation in Passster Plugin for WordPress
CVE-2026-17559

5.3MEDIUM

Key Information:

Vendor

WordPress
Status
Passster
Vendor
CVE Published:
21 August 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-17559?

The Passster plugin for WordPress prior to version 4.3.9 contains a flaw that allows unauthenticated attackers to bypass globally set password protections due to improper comparison of REST API endpoint paths. Instead of accurately matching resolved routes, the plugin evaluates paths as unanchored substrings of the request URI. This oversight enables attackers to access and read the content of posts and pages that are intended to be password-protected.

Affected Version(s)

Passster 4.3.3 < 4.3.9

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-17559 - Proof of Concept

References

https://wpscan.com/vulnerability/28a48c1c-e162-4e8a-b450-...
exploitvdb-entrytechnical-description

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Erwan LR (WPScan)
WPScan
.