CVE-2026-19760
Deferred Deferred - Pending Action

Stored XSS in WP Fastest Cache WordPress Plugin

Publication date: 2026-08-26

Last updated on: 2026-08-26

Assigner: Wordfence

Description
The WP Fastest Cache – WordPress Cache Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via HTTP Host Header in all versions up to, and including, 1.5.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the Polylang or Polylang Pro plugin to be active and the Combine JS option to be enabled, as these conditions trigger the vulnerable Host-header-to-URL code path that writes attacker-controlled script src values into the shared page-cache file served to all subsequent visitors.

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Meta Information

Published
2026-08-26
Last Modified
2026-08-26
Generated
2026-08-26
AI Q&A
2026-08-26
EPSS Evaluated
N/A
NVD
CVE-2026-19760
EUVD
EUVD-2026-66249

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
wp_faster_cache wp_faster_cache to 1.5.0 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This is a Stored Cross-Site Scripting (XSS) vulnerability in the WP Fastest Cache WordPress plugin. It allows unauthenticated attackers to inject malicious scripts into web pages via the HTTP Host Header. The scripts execute when users visit the affected pages. Exploitation requires the Polylang or Polylang Pro plugin to be active and the Combine JS option enabled.

Detection Guidance

Check if the WP Fastest Cache plugin is installed and its version is up to 1.5.0. Verify if Polylang or Polylang Pro is active and the Combine JS option is enabled. Inspect cached pages for injected scripts in the Host header.

Impact Analysis

Attackers could steal user sessions, redirect visitors to malicious sites, or perform actions on behalf of users. Since the injected scripts are stored in cached pages, all subsequent visitors to those pages are affected. This could lead to data theft, account compromise, or malware distribution.

Compliance Impact

This vulnerability could violate GDPR by exposing user data through script injection or enabling unauthorized access to personal information. For HIPAA, it may risk protected health information exposure if exploited on healthcare-related sites. Compliance failures could result in legal penalties or fines.

Mitigation Strategies

Update the WP Fastest Cache plugin to the latest version. Disable the Combine JS option in WP Fastest Cache settings. Deactivate Polylang or Polylang Pro if not required. Clear all cached pages to remove any injected scripts.

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