What’s Vulnerable › Vulnerabilities

CVE-2021-39357: Leaky Paywall <= 4.16.5 Authenticated Stored Cross-Site Scripting

• Severity: medium (CVSS 4.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-10-21 · updated 2026-06-17
• Weakness: CWE-79

Description

The Leaky Paywall WordPress plugin is vulnerable to Stored Cross-Site Scripting due to insufficient input validation and sanitization via the ~/class.php file which allowed attackers with administrative user access to inject arbitrary web scripts, in versions up to and including 4.16.5. This affects multi-site installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.

Affected products

• ZEEN101 Leaky Paywall: through 4.16.5

References

• https://github.com/BigTiger2020/word-press/blob/main/Leaky%20Paywall.md
• https://plugins.trac.wordpress.org/changeset/2615195/leaky-paywall/trunk/class.php
• https://wordfence.com/vulnerability-advisories/#CVE-2021-39357
• https://github.com/BigTiger2020/word-press/blob/main/Leaky%20Paywall.md
• https://plugins.trac.wordpress.org/changeset/2615195/leaky-paywall/trunk/class.php
• https://wordfence.com/vulnerability-advisories/#CVE-2021-39357

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