league/commonmark: DisallowedRawHtml extension bypass via whitespace in HTML tag names (thephpleague commonmark)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.23 % · percentile 13 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
league/commonmark is a PHP Markdown parser. Prior to version 2.8.1, the DisallowedRawHtml extension can be bypassed by inserting a newline, tab, or other ASCII whitespace character between a disallowed HTML tag name and the closing >. For example, <script\n> would pass through unfiltered and be rendered as a valid HTML tag by browsers. This is a cross-site scripting (XSS) vector for any application that relies on this extension to sanitize untrusted user input. All applications using the DisallowedRawHtml extension to process untrusted markdown are affected. Applications that use a dedicated HTML sanitizer (such as HTML Purifier) on the rendered output are not affected. This issue has been patched in version 2.8.1.
Weaknesses (CWE)
- CWE-79 — Improper Neutralization of Input During Web Page Generation
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | MEDIUM 5.1 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N | GitHub_M |
| CVSS 4.0 | MEDIUM 5.1 | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-4v6x-c7xx-hw9f — CommonMark has DisallowedRawHtml extension bypass via whitespace in HTML tag names
European references
- ENISA EUVD · EUVD-2026-10168
- GCVE · GCVE-0-2026-30838
Affected configurations (NVD CPE)
cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*< 2.8.1
Affected products
| Product | Versions |
|---|---|
| thephpleague · commonmark | affected < 2.8.1 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |