CVE-2026-49978

ADVISORY - github

Summary

If the HTML you give it contains a element, and inside that template there's an element with a shadow DOM attached to it, DOMPurify quietly skips over the shadow contents. Whatever the attacker put in there - an image with an onerror handler, a link with a javascript: URL, even a full script - survives untouched. The moment the application uses that template the way templates are meant to be used (cloning it and inserting the result into the page), the malicious payload comes along and runs as if it had never been sanitized. From there an attacker gets everything XSS normally gets them: session cookies, stored tokens, the ability to act as the user, and the ability to leave persistent payloads behind for the next person who visits.

advisory.pdf

poc.html

EPSS Score: 0.00038 (0.116)

Common Weakness Enumeration (CWE)

ADVISORY - github

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')


GitHub

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

5.1medium
PackageTypeOS NameOS VersionAffected RangesFix Versions
dompurifynpm--<=3.4.63.4.7

CVSS:4 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.

The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.

The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

Successful exploitation of this vulnerability requires a targeted user to perform specific, conscious interactions with the vulnerable system and the attacker's payload, or the user's interactions would actively subvert protection mechanisms which would lead to exploitation of the vulnerability. Examples include: importing a file into a vulnerable system in a specific manner placing files into a specific directory prior to executing code submitting a specific string into a web application (e.g. reflected or self XSS) dismiss or accept prompts or security warnings prior to taking an action (e.g. opening/editing a file, connecting a device).

There is no loss of confidentiality within the Vulnerable System.

There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Subsequent System.

There is no loss of integrity within the Vulnerable System.

Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Subsequent System.

There is no impact to availability within the Vulnerable System.

There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

minimos

CREATED

UPDATED

ADVISORY ID

MINI-8xm4-5vx6-cp5h

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY