CVE-2026-14574: Prototype Pollution

Description

In Eclipse Theia versions 0.7.0 and up until including 1.73.1, the `PreferenceUtils.merge` function in `@theia/core` recursively merges preference values without rejecting prototype-related keys (`__proto__`, `constructor`, `prototype`). Because this function is invoked by `PreferenceServiceImpl.doResolve` for every preference resolution across scopes (default, user, workspace, folder), a crafted preference value in a workspace settings file (`.theia/settings.json` or `.vscode/settings.json`) can pollute `Object.prototype` when the user opens the workspace, potentially altering application logic across the Theia process.

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Weakness Type (CWE)

CWE-1321 CWE-1321

References

Other References

https://github.com/eclipse-theia/theia/security/advisories/GHSA-f3w9-qfw3-xr32 https://gitlab.eclipse.org/security/cve-assignment/-/work_items/157 https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/567 https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/567

Frequently Asked Questions

What is CVE-2026-14574? +

In Eclipse Theia versions 0.7.0 and up until including 1.73.1, the `PreferenceUtils.merge` function in `@theia/core` recursively merges preference values without rejecting prototype-related keys (`__proto__`, `constructor`, `prototype`). Because this function is invoked by `PreferenceServiceImpl.doResolve` for every preference resolution across scopes (default, user, workspace, folder), a crafted preference value in a workspace settings file (`.theia/settings.json` or `.vscode/settings.json`) can pollute `Object.prototype` when the user opens the workspace, potentially altering application logic across the Theia process.

How do I check if I'm vulnerable to CVE-2026-14574? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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