CVE-2026-3375: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in litespeedtech LiteSpeed Cache
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.
AI Analysis
Technical Summary
CVE-2026-3375 is a stored cross-site scripting vulnerability in the LiteSpeed Cache WordPress plugin (up to version 7.7). The vulnerability exists in the /wp-json/litespeed/v1/notify_ccss and /wp-json/litespeed/v1/notify_ucss REST API endpoints, which accept CSS content from QUIC.cloud callback notifications and store it to disk without sanitization. This stored content is later rendered inline on frontend page loads without proper output escaping, enabling script injection. The endpoints rely on IP-based access control, which can be bypassed when the WordPress site is behind certain reverse proxies, load balancers, or CDNs, allowing unauthenticated attackers to exploit the vulnerability. The CVSS 3.1 base score is 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N), indicating a high severity vulnerability with network attack vector, low attack complexity, no privileges or user interaction required, and impacts on confidentiality and integrity with scope change.
Potential Impact
Successful exploitation allows unauthenticated attackers to inject arbitrary JavaScript into the CSS content served by the vulnerable WordPress site. This can lead to cross-site scripting attacks affecting site visitors, potentially resulting in session hijacking, defacement, or other client-side impacts. The vulnerability affects confidentiality and integrity but does not impact availability. The IP-based access control can be bypassed under certain deployment configurations, increasing the risk of exploitation.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, administrators should review their reverse proxy, load balancer, or CDN configurations to ensure that IP-based access controls on the affected REST API endpoints cannot be bypassed. Consider restricting access to these endpoints to trusted IPs only and monitoring for suspicious requests targeting /wp-json/litespeed/v1/notify_ccss and /wp-json/litespeed/v1/notify_ucss. Avoid deploying the plugin in configurations that weaken IP-based protections.
CVE-2026-3375: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in litespeedtech LiteSpeed Cache
Description
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.
CVSS v3.1
Score 7.2high
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-3375 is a stored cross-site scripting vulnerability in the LiteSpeed Cache WordPress plugin (up to version 7.7). The vulnerability exists in the /wp-json/litespeed/v1/notify_ccss and /wp-json/litespeed/v1/notify_ucss REST API endpoints, which accept CSS content from QUIC.cloud callback notifications and store it to disk without sanitization. This stored content is later rendered inline on frontend page loads without proper output escaping, enabling script injection. The endpoints rely on IP-based access control, which can be bypassed when the WordPress site is behind certain reverse proxies, load balancers, or CDNs, allowing unauthenticated attackers to exploit the vulnerability. The CVSS 3.1 base score is 7.2 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N), indicating a high severity vulnerability with network attack vector, low attack complexity, no privileges or user interaction required, and impacts on confidentiality and integrity with scope change.
Potential Impact
Successful exploitation allows unauthenticated attackers to inject arbitrary JavaScript into the CSS content served by the vulnerable WordPress site. This can lead to cross-site scripting attacks affecting site visitors, potentially resulting in session hijacking, defacement, or other client-side impacts. The vulnerability affects confidentiality and integrity but does not impact availability. The IP-based access control can be bypassed under certain deployment configurations, increasing the risk of exploitation.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, administrators should review their reverse proxy, load balancer, or CDN configurations to ensure that IP-based access controls on the affected REST API endpoints cannot be bypassed. Consider restricting access to these endpoints to trusted IPs only and monitoring for suspicious requests targeting /wp-json/litespeed/v1/notify_ccss and /wp-json/litespeed/v1/notify_ucss. Avoid deploying the plugin in configurations that weaken IP-based protections.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-02-28T00:59:32.665Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a16a557e29bf47b50a64072
Added to database: 5/27/2026, 8:03:35 AM
Last enriched: 5/27/2026, 8:33:33 AM
Last updated: 5/29/2026, 4:27:27 PM
Views: 16
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.