CVE-2021-24964Public exploitNetwork attack vector

Unauthenticated stored XSS via spoofed cloud IP

Published Jan 3, 2022 · Updated May 22, 2025

Stored XSS in LiteSpeed Cache for WordPress before 4.4.4 allows remote attackers to execute scripts in visitors' browsers. The notify_ccss REST endpoint trusts a QUIC.cloud IP supplied in X-Forwarded-For and stores attacker-controlled CSS without sanitizing or escaping it. Load CSS Asynchronously must be enabled, and execution occurs when a user visits an affected page.

CVSS severity6.5
Medium
EPSS probability1.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in LiteSpeed Cache for WordPress before 4.4.4 allows remote attackers to execute scripts in visitors' browsers. The notify_ccss REST endpoint trusts a QUIC.cloud IP supplied in X-Forwarded-For and stores attacker-controlled CSS without sanitizing or escaping it. Load CSS Asynchronously must be enabled, and execution occurs when a user visits an affected page.

The record

CVE
CVE-2021-24964
Published
Jan 3, 2022
Updated
May 22, 2025
Vendor
LiteSpeed Technologies
Product
LiteSpeed Cache for WordPress
Classifications
CWE-79, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 3, 2022CVE publishedPublication date reported by the CVE source.
  2. May 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4.4 <4.4.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LiteSpeed Technologies · LiteSpeed Cache for WordPressversion=4.4.4 <4.4.4

Published CVSS scores

6.5WordfenceCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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