CVE-2026-118492
Received Received - Intake

Cross-Site Scripting in Eclipse Langium Langium-sprotty

Publication date: 2026-11-09

Last updated on: 2026-11-09

Assigner: Eclipse Foundation

Description
In Eclipse Langium versions 3.0.0 and later, the langium-sprotty package does not HTML-escape diagnostic messages before rendering them in the default hover popup provided by `addHoverPopupHandler`. If a Langium grammar allows cross-reference text to contain HTML markup (such as through a STRING terminal), an unresolved cross-reference produces a diagnostic message that includes the literal ref text. When a Sprotty diagram is opened for a malicious source file under these conditions, and a user hovers over the corresponding error marker, attacker-controlled JavaScript can execute in the browser or webview.

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Meta Information

Published
2026-11-09
Last Modified
2026-11-09
Generated
2026-11-09
AI Q&A
2026-11-09
EPSS Evaluated
N/A
NVD
CVE-2026-118492
EUVD
EUVD-2026-120085

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
Eclipse Foundation Eclipse Langium From 3.0.0 (inc) to 4.4.0 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
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.

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Executive Summary

This vulnerability is a cross-site scripting (XSS) issue in Eclipse Langium's langium-sprotty package versions 3.0.0 and later. It occurs because diagnostic messages are not HTML-escaped before being rendered in hover popups. If a grammar allows HTML markup in cross-reference text, an unresolved reference produces a diagnostic message containing attacker-controlled text. When a user hovers over the error marker in a Sprotty diagram, malicious JavaScript can execute in the browser or webview.

Detection Guidance

This vulnerability is specific to the Eclipse Langium langium-sprotty package versions 3.0.0 through 4.4.2. To detect it, check if your system uses these versions by inspecting package dependencies or running commands like npm list langium-sprotty or yarn list langium-sprotty.

Impact Analysis

This vulnerability requires specific conditions to exploit: a language must depend on langium-sprotty, use addHoverPopupHandler(), generate diagrams with diagnostic markers containing attacker-controlled characters, and the victim must hover over the marker. If exploited, it could allow an attacker to execute arbitrary JavaScript in the user's browser or webview.

Compliance Impact

This vulnerability could potentially affect compliance with GDPR and HIPAA by enabling cross-site scripting (XSS) attacks. If exploited, it may allow unauthorized execution of JavaScript in a user's browser, which could lead to data theft, manipulation, or unauthorized access to sensitive information. This violates principles of data integrity and confidentiality required by these regulations.

Mitigation Strategies

Update the langium-sprotty package to a version that includes the fix for HTML escaping in diagnostic messages. If updating is not possible, avoid using addHoverPopupHandler() or ensure untrusted diagnostic messages are properly sanitized before rendering.

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