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

Q: What is CVE-2026-18978?

CVE-2026-18978 is a high-severity cross-site scripting vulnerability in litespeedtech LiteSpeed Cache, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

High 7.2 Published 28 Aug 2026 Updated 28 Aug 2026

Unauthenticated attackers can inject arbitrary scripts via comments in LiteSpeed Cache, potentially leading to code execution or account takeover.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-18978?

CVE-2026-18978 is a high-severity cross-site scripting vulnerability in litespeedtech LiteSpeed Cache, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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. ", <, >) placed inside an allowed element such as <code> 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.

Weakness: CWE-79

Which versions are affected by CVE-2026-18978?

How do I fix CVE-2026-18978?

No fix has been published for CVE-2026-18978 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-18978 being exploited?

There is no known exploitation of CVE-2026-18978 in the wild and no public exploit code.

Sources

Also known as GHSA-rm48-v2jm-fxxq.