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.

CVSS 4.0

5.7CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:L/VI:H/VA:L/SC:N/SI:L/SA:L

CVSS 3.1

6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 33% of CVEs (scores of 2026-10-25)

CWE

CWE-1321

Published

2026-08-05

Modified

2026-10-23

Record from

the NVD, synced 2026-10-24

Affected

• eclipse:theia

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

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