CVE-2026-14574: Eclipse Theia

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Eclipse Theia: from 0.7.0, before 1.74.0 (fixed in 1.74.0)

Published 2026-08-05. Last modified 2026-08-07.