In lsquic before 4.9.0, the HTTP/3 implementation can use an excessive amount of memory because the number of buffered header sets is not limited, as demonstrated by a QPACK amplification attack. This is related to header_out_dynamic_entry and es_max_header_list_size.
OpenLiteSpeed versions before 1.9.3 have a local privilege escalation vulnerability due to a TOCTOU race condition in the admin update script lsup.sh. This script runs update packages from a directory writable by the nobody user without verifying them, allowing an attacker with control over the nobody web process to replace the update package and execute arbitrary code as root during the next update.
The LiteSpeed Cache plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'esi' parameter in all versions up to, and including, 7.9 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. Exploitation requires that the attacker supply a validly signed 'esi' value in the GET query string while submitting a separate attacker-controlled 'esi' payload as a POST body field, relying on PHP's default $_REQUEST merge order to have the POST value take precedence at the point of execution.
LiteSpeed Cache plugin for WordPress versions up to and including 7.7 is vulnerable to stored cross-site scripting (XSS) due to improper input neutralization in crafted <img> tag attributes. The vulnerability arises from a flawed regular expression used to strip width and height attributes when certain image features are enabled. Authenticated users with Author-level access or higher can inject arbitrary scripts that execute when other users view the affected pages.
LiteSpeed Cache plugin for WordPress versions up to and including 7.8.1 is vulnerable to a stored cross-site scripting (XSS) attack via comment content. The vulnerability arises from insufficient input sanitization and output escaping, allowing unauthenticated attackers to inject arbitrary scripts that execute when users view the injected page. Exploitation requires that the site allows users with previously approved comments to write new comments and that the require_name_email setting is disabled.
LiteSpeed cPanel plugin before 2.4.8 (as distributed in LiteSpeed WHM PlugIn before 5.3.2.0) mishandles symlinks provided by a user with FTP or web shell access on a shared hosting server running CloudLinux/CageFS, as exploited in the wild in May 2026.
The LiteSpeed Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the /wp-json/litespeed/v1/notify_ccss and /wp-json/litespeed/v1/notify_ucss REST API endpoints in all versions up to, and including, 7.7. These endpoints accept CSS content from QUIC.cloud callback notifications and store it to disk without sanitization. The stored content is later rendered inline frontend page loads without output escaping. The access control protecting these endpoints is IP-based validation that can potentially be bypassed when the WordPress site is deployed behind a reverse proxy, load balancer, or CDN with certain configurations. This makes it possible for unauthenticated attackers, under certain conditions, to inject arbitrary JavaScript into CCSS/UCSS content.
LiteSpeed User-End cPanel Plugin before 2.4.5 allows privilege escalation (possibly to root), as exploited in the wild in May 2026. Detection is best done via a command line of grep -rE "cpanel_jsonapi_func=redisAble" /var/cpanel/logs /usr/local/cpanel/logs/ 2>/dev/null in Bash. If you get no output, you have not been hit with exploitation of the vulnerability. If there is output, we recommend you examine the IP addresses in the list, determine if they are valid IP addresses, and if not, block them. To determine damage done, examine the system logs for use by the detected IP addresses. The issue is related to mishandling of Redis enable/disable features. The recommended minimum version is 2.4.7.
OpenLiteSpeed and LSWS Enterprise provided by LiteSpeed Technologies contain an OS command injection vulnerability. An arbitrary OS command may be executed by an attacker with the administrative privilege.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in LiteSpeed Technologies LiteSpeed Cache litespeed-cache allows Stored XSS.This issue affects LiteSpeed Cache: from n/a through <= 6.5.2.
The LiteSpeed Cache plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via URLs in all versions up to, and including, 7.5.0.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in LiteSpeed Technologies LiteSpeed Cache litespeed-cache allows Stored XSS.This issue affects LiteSpeed Cache: from n/a through <= 6.5.0.2.