CVE-2021-39357

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.

• CWE-79

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

Published

Oct 21, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2021-39351The WP Bannerize WordPress plugin is vulnerable to authentic…6.5
• CVE-2021-39352The Catch Themes Demo Import WordPress plugin is vulnerable …7.2
• CVE-2021-39353The Easy Registration Forms WordPress plugin is vulnerable t…8.8
• CVE-2021-39354The Easy Digital Downloads WordPress plugin is vulnerable to…4.8
• CVE-2021-39355The Indeed Job Importer WordPress plugin is vulnerable to St…4.8
• CVE-2021-39356The Content Staging WordPress plugin is vulnerable to Stored…4.8
• CVE-2021-39358In GNOME libgfbgraph through 0.2.4, gfbgraph-photo.c does no…5.9
• CVE-2021-39359In GNOME libgda through 6.0.0, gda-web-provider.c does not e…5.9
• CVE-2021-39360In GNOME libzapojit through 0.0.3, zpj-skydrive.c does not e…5.9
• CVE-2021-39361In GNOME evolution-rss through 0.3.96, network-soup.c does n…5.9
• CVE-2021-39362An XSS issue was discovered in ReCaptcha Solver 5.7. A respo…6.1
• CVE-2021-39363Honeywell HDZP252DI 1.00.HW02.4 and HBW2PER1 1.000.HW01.3 de…9.8