CVE-2018-1000874: Cebe Markdown

Medium severity, CVSS 6.1. EPSS: 0.8% chance of exploitation in the next 30 days.

PHP cebe markdown parser version 1.2.0 and earlier contains a Cross Site Scripting (XSS) vulnerability in all distributed parsers allowing a malicious crafted script to be executed that can result in the lose of user data and sensitive user information. This attack can be exploited by crafting a three backtick wrapped payload with a character in front: L: "```<script>alert();</script>```". NOTE: This has been argued as a non-issue (see references) since it is not the parser's job to sanitize malicious code from a parsed document

Affected products

• Cebe Markdown: up to and including 1.2.0

Published 2018-12-20. Last modified 2026-06-17.