CVE-2026-60009 File upload in Eclipse Theia
Unauthenticated attackers can write arbitrary files via a cross-origin request, potentially achieving remote code execution in browser-based deployments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-60009?
CVE-2026-60009 is a high-severity vulnerability in Eclipse Theia, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
In Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend binds `POST /file-upload` in every filesystem-enabled deployment. The handler takes an attacker-supplied absolute path from the multipart `uri` field and calls `fs.move(tmp, target, { overwrite: true })` with no workspace confinement and no authentication. In browser (non-Electron) deployments the connection token is enforced only on WebSocket upgrades; the HTTP middleware in `@theia/core` re-issues the cookie and calls `next()` without rejecting tokenless HTTP requests. Because `multipart/form-data` is a CORS-safelisted request type, a cross-origin web page can trigger the write with no preflight and no credentials, resulting in an unauthenticated arbitrary file write outside the workspace to any absolute path the backend process can write. This can escalate to remote code execution, for example by overwriting a startup-executed file such as `~/.bashrc`. Electron mode uses a separate `ElectronSecurityToken` and is not affected via this path.
Which versions are affected by CVE-2026-60009?
It affects 1 product.
Products include Eclipse Theia.
How do I fix CVE-2026-60009?
No fix has been published for CVE-2026-60009 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-60009 being exploited?
There is no known exploitation of CVE-2026-60009 in the wild and no public exploit code.
Other vulnerabilities in Eclipse Theia
- CVE-2021-34436 XML external entity in Eclipse Theia
- CVE-2020-27224 Cross-site Scripting (XSS) in Eclipse Theia
- CVE-2021-34435 Remote code execution in Eclipse Theia
- CVE-2026-44688 [Eclipse Theia] Indirect Prompt Injection via Adversarial Workspace File and Directory Names in AI Chat
- CVE-2026-44691 [Eclipse Theia] Arbitrary Command Execution via Untrusted Workspace Task Definitions
Sources
Also known as GHSA-2mw2-h8hj-xpjg, GHSA-62f6-wcvg-54h3.