# 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:** Medium 5.7 (`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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 5 Aug 2026
- **Updated:** 5 Aug 2026
- **Also known as:** GHSA-5f8h-2xph-wwxv, GHSA-f3w9-qfw3-xr32

## What is CVE-2026-14574?

CVE-2026-14574 is a medium-severity vulnerability in Eclipse Theia, published on 5 Aug 2026. 

### Official 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.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-14574?

It affects 1 product.


Products: Eclipse Theia.

## How do I fix CVE-2026-14574?

No fix has been published for CVE-2026-14574 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-14574 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-14574 exists.

## Other vulnerabilities in Eclipse Theia

- [CVE-2021-34436](https://insights.sbomify.com/CVE-2021-34436/): XML external entity in Eclipse Theia (critical 9.8)
- [CVE-2020-27224](https://insights.sbomify.com/CVE-2020-27224/): Cross-site Scripting (XSS) in Eclipse Theia (critical 9.6)
- [CVE-2026-60009](https://insights.sbomify.com/CVE-2026-60009/): File upload in Eclipse Theia (high 8.8)
- [CVE-2021-34435](https://insights.sbomify.com/CVE-2021-34435/): Remote code execution in Eclipse Theia (high 8.8)
- [CVE-2026-44688](https://insights.sbomify.com/CVE-2026-44688/): [Eclipse Theia] Indirect Prompt Injection via Adversarial Workspace File and Directory Names in AI Chat (high 8.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-14574 and fix it if it is affected.

What it is: CVE-2026-14574 is a medium-severity vulnerability in Eclipse Theia, published on 5 Aug 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-14574 exists.

Affected product: Eclipse Theia. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-14574/ (Markdown: https://insights.sbomify.com/CVE-2026-14574/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-14574
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-14574
- OSV: https://osv.dev/vulnerability/CVE-2026-14574

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-14574/
Summaries are generated and may contain mistakes; the official description above is the record.