VDB-349684 · CVE-2026-30838 · GHSA-4v6x-c7xx-hw9f

thephpleague commonmark up to 2.8.0 PHP Markdown Parser cross site scripting

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.7	$0-$5k	0.00

Summaryinfo

A vulnerability was found in thephpleague commonmark up to 2.8.0. It has been declared as problematic. Impacted is an unknown function of the component PHP Markdown Parser. Executing a manipulation can lead to cross site scripting. The identification of this vulnerability is CVE-2026-30838. The attack may be launched remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in thephpleague commonmark up to 2.8.0. It has been declared as problematic. This vulnerability affects some unknown processing of the component PHP Markdown Parser. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-30838 since 03/05/2026. The exploitation appears to be easy. The attack can be initiated remotely. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 2.8.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1001). Once again VulDB remains the best source for vulnerability data.

Affected

Open Source Snipe-IT

Productinfo

Vendor

thephpleague

Name

commonmark

Version

Website

Product: https://github.com/thephpleague/commonmark/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.7

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.1
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: commonmark 2.8.1

Timelineinfo

03/05/2026 CVE reserved
03/07/2026 +2 days Advisory disclosed
03/07/2026 +0 days VulDB entry created
04/09/2026 +33 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-4v6x-c7xx-hw9f
Status: Confirmed

CVE: CVE-2026-30838 (🔒)
GCVE (CVE): GCVE-0-2026-30838
GCVE (VulDB): GCVE-100-349684
CERT Bund: WID-SEC-2026-1001 - Snipe-IT: Mehrere Schwachstellen ermöglichen Umgehen von Sicherheitsvorkehrungen und potenziell Cross-Site Scripting

Entryinfo

Created: 03/07/2026 18:02
Updated: 04/09/2026 08:56
Changes: 03/07/2026 18:02 (68), 03/08/2026 15:36 (1), 03/12/2026 14:39 (12), 04/09/2026 08:56 (7)
Complete: 🔍
Cache ID: 216::103