CVE-2026-105829

Medium

Description

League CommonMark from 1.3.0 before 2.10.2 contains a cross-site scripting vulnerability that allows users posting Markdown to bypass the DisallowedRawHtml extension by ending raw HTML with a bare disallowed tag name. Attackers can place a lone <script or <iframe line followed by a block supplying attributes like src or onload, executing stored scripts in viewers' browsers under default GFM settings.

SeverityMedium

CVSS6.1

Exploit probability—

ProductLeague/commonmark

PublishedOct 8, 2026

First seenOct 8, 2026

Weakness typeCWE-80CWE-80

How to fix

Update

league/commonmark2.10.2 or later

Vendor advisories

github.com/thephpleague/commonmark/security/advisories/GHSA-97jj-33gv-5xf9

Affected products

Product	Affected versions	Fixed in
league/commonmarkPackagist	1.3.0 ≤ v < 2.10.2	2.10.2

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