Eclipse Theia up to 1.73.1 Preference Utils PreferenceUtils.merge prototype pollution

Summaryinfo

A vulnerability, which was classified as critical, has been found in Eclipse Theia up to 1.73.1. This affects the function PreferenceUtils.merge of the component Preference Utils. Performing a manipulation results in prototype pollution. This vulnerability was named CVE-2026-14574. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability classified as critical has been found in Eclipse Theia up to 1.73.1. This affects the function PreferenceUtils.merge of the component Preference Utils. The manipulation with an unknown input leads to a prototype pollution vulnerability. CWE is classifying the issue as CWE-1321. The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-14574 since 07/03/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

Upgrading to version 1.74.0 eliminates this vulnerability.

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Productinfo

Vendor

• Eclipse

Name

• Theia

Version

• 1.73.0
• 1.73.1

License

• open-source

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CPE 2.2info

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