CVE-2026-3129

LiteSpeed Cache <= 7.7 - Authenticated (Author+) Stored Cross-Site Scripting via img Tag Attributes

2026-08-27 15:15
stealthcopter

Strategic Overview

Status
Patched in 7.8
Affected Plugin
LiteSpeed Cache
Affected Version
<= 7.7
CVSS
6.4Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-3129
View all LiteSpeed Cache vulnerabilities

At a glance

CVE-2026-3129 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the LiteSpeed Cache WordPress plugin, affecting versions <= 7.7. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Author level or above. The issue is fixed in version 7.8; sites on affected versions should update now. Disclosed August 2026, reported by stealthcopter.

Vulnerability Overview

The LiteSpeed Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via crafted `<img>` tag attributes in all versions up to, and including, 7.7. This is due to a flawed regular expression that is used to strip `width` and `height` attributes from images when the "Lazy Load Images" and "Add Missing Sizes" features are enabled. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts in pages that execute whenever a user accesses an injected page.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

LiteSpeed Cache <= 7.7 carries this weakness at and, and reaching it takes an account at Author level or above. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For LiteSpeed Cache the fix is 7.8: builds <= 7.7 are affected, anything from 7.8 onward is not.

Remediation

Update to version 7.8, or a newer patched version

How does WordSec protect against this?

An attacker needs Author access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: LiteSpeed Cache 7.8 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-3129https://www.wordfence.com/threat-intel/vulnerabilities/id/c107674d-173f-49cf-b329-e7bffaee841dhttps://nvd.nist.gov/vuln/detail/CVE-2026-3129

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C