EUVD-2026-66249
GHSA-q9vw-j254-6x3w
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
AC:H reflects the two non-default prerequisites outside attacker control (Polylang active and Combine JS enabled); all other metrics match the vulnerability's stored XSS network impact.
Primary rating from Vendor (Wordfence).
CVSS VectorVendor: Wordfence
Lifecycle Timeline
2DescriptionCVE.org
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.
AnalysisAI
Stored Cross-Site Scripting in WP Fastest Cache (WordPress plugin, all versions through 1.5.0) allows unauthenticated remote attackers to inject persistent JavaScript by supplying a crafted HTTP Host header that the plugin writes into shared page-cache files, which are then served to all subsequent visitors. Exploitation requires two co-present non-default conditions: the Polylang or Polylang Pro multilingual plugin must be installed and active, and the 'Combine JS' option must be enabled in WP Fastest Cache settings, both of which activate the vulnerable Host-header-to-URL code path in js-utilities.php. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Three specific conditions must all be simultaneously true for this vulnerability to be exploitable: (1) WP Fastest Cache version 1.5.0 or earlier must be installed and active on the WordPress site; (2) the Polylang or Polylang Pro multilingual plugin must be installed and active - this is the prerequisite that triggers the Host-header-to-URL code path within the JS combination logic; (3) the 'Combine JS' option must be explicitly enabled in WP Fastest Cache settings - this is a non-default feature that must be deliberately activated by the site administrator. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.2 score and Scope:Changed metric (S:C) appropriately reflect the stored, persistent nature of this XSS - a single malicious request can poison a cache file subsequently read by all site visitors, amplifying impact well beyond a typical reflected XSS. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | A fixed version beyond 1.5.0 is strongly implied by the 'up to and including 1.5.0' scope language, but no specific patched release version was identified in the available data; monitor the Wordfence advisory at https://www.wordfence.com/threat-intel/vulnerabilities/id/69a22238-88e8-4ff5-8e2b-8c58a04ff154 and the WordPress plugin repository for an updated release. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, audit your WordPress installation to identify if WP Fastest Cache version 1.5.0 or earlier is deployed, and verify whether both the Polylang plugin and 'Combine JS' option are enabled; if both conditions exist, immediately disable the 'Combine JS' option in WP Fastest Cache settings to close the attack vector. …
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External POC / Exploit Code
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