CVE-2026-18978 HIGH

CVE-2026-18978: LiteSpeed Cache <= 7.8.1 - Unauthenticated Stored Cross-Site Scripting via Comment Content

Vendor Litespeedtech
Product LiteSpeed Cache
Weakness CWE-79 · XSS
Published August 28, 2026
Last update August 28, 2026

CVSS base score

7.2/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

What the vulnerability does

01Description

The LiteSpeed Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content in all versions up to, and including, 7.8.1 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. A comment payload crafted exclusively from decimal numeric character references (e.g. &#34;, &#60;, &#62;) placed inside an allowed element such as &lt;code&gt; bypasses WordPress's wp_kses sanitization, as kses does not treat a data-settings="..." substring within text content as an HTML attribute, allowing the malicious payload to reach the vulnerable function. For this to be exploitable, the site must allow users with previously approved comments to write new comments, and the require_name_email setting must be disabled.

Explanation of Vulnerability in Simple Terms

02Summary

LiteSpeed Cache versions up to 7.8.1 contain a cross-site scripting (XSS) vulnerability that allows attackers to inject malicious scripts into cached pages. The vulnerability can affect multiple users viewing the same cached content. No authentication is required to exploit this issue. Site administrators should update to a version newer than 7.8.1.

What an attacker can do

03Attacker Capabilities

Inject malicious JavaScript that runs in visitors' browsers when they view cached pages.

Potential impact on your site

04Site Impact

Visitors' browsers could execute attacker-controlled scripts, potentially stealing session tokens or redirecting users.

Conditions required to exploit

05Prerequisites

Network access only; no authentication or user interaction required.

Key dates

06Disclosure timeline

August 28, 2026 CVE published

Related vulnerabilities

08Related CVE