CVE-2026-14574: eclipse foundation eclipse theia Prototype Pollution

Vulnerability summary

CVE-2026-14574 is a medium (CVSS 6.5) Prototype Pollution vulnerability in eclipse foundation eclipse theia. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 32.2% of scored vulnerabilities. 2 public exploits are recorded.

Timeline

1. 05-08-2026
   PublishedVulnerability first disclosed.
2. 05-08-2026
   Last modifiedVulnerability information updated.

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.

• CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')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.