Prototype Pollution in Eclipse Theia
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.
Vulnerability class: Prototype Pollution
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (33.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Eclipse Theia
- Eclipse Foundation Theia — versions 0.7.0
Weakness classification (CWE)
References
- github.com/eclipse-theia/theia/security/advisories/GHSA-f3w9-qfw3-xr32 (Broken Link)
- gitlab.eclipse.org/security/cve-assignment/-/work_items/157 (Vendor Advisory)
- gitlab.eclipse.org/security/vulnerability-reports/-/issues/567 (Exploit, Mitigation, Issue Tracking, Vendor Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-14574?
- CVE-2026-14574 is a medium-severity vulnerability in Eclipse Theia, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 6.5/10. Published 2026-08-05.
- How severe is CVE-2026-14574?
- Medium severity. CVSS v3 base score is 6.5 out of 10.