← Vulnerability feed

Vulnerability record · CVE-2026-61891 · published 5 August 2026

CVE-2026-61891: Eclipse theia path traversal vulnerability

Eclipse · Theia

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.

7.5 CVSS 3.1 High EPSS 0.53% · top 57.3% CWE-22 · Path traversalCWE-36 · CWE-36
7.5CVSS 3.1 base score
0.53%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
7 Aug 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/eclipse-theia/theia/security/advisories/GHSA-qqc8-9538-25v4 Broken Link
https://gitlab.eclipse.org/security/cve-assignment/-/work_items/176 Vendor Advisory
https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/570 Issue TrackingVendor Advisory

Track CVE-2026-61891 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-34436Eclipse theia path traversal vulnerabilityIn Eclipse Theia 0.1.1 to 0.2.0, it is possible to exploit the default build to obtain remote code execution (and XXE) via the theia-xml-extension. T…EPSS 2.2%9.6CVE-2020-27224Eclipse theia cross-site scripting vulnerabilityIn Eclipse Theia versions up to and including 1.2.0, the Markdown Preview (@theia/preview), can be exploited to execute arbitrary code.EPSS 2.6%8.8CVE-2026-60009Eclipse theia path traversal vulnerabilityIn Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend binds `POST /file-upload` in every filesystem-enabled deploymen…EPSS 0.44%8.8CVE-2021-34435Eclipse theia origin validation error vulnerabilityIn Eclipse Theia 0.3.9 to 1.8.1, the "mini-browser" extension allows a user to preview HTML files in an iframe inside the IDE. But with the way it is…EPSS 0.60%8.4CVE-2026-44691Eclipse theia inclusion from untrusted sphere vulnerabilityIn Eclipse Theia versions prior to 1.69.0, custom task definitions in workspace files (e.g. .theia/tasks.json, .vscode/tasks.json) could be executed …EPSS 0.41%8.4CVE-2026-46580Eclipse theia inclusion from untrusted sphere vulnerabilityIn Eclipse Theia versions prior to 1.71.0, files matching the pattern .prompts/*.prompttemplate in a workspace were automatically loaded and could ov…EPSS 0.51%8.4CVE-2026-44688Eclipse theia inclusion from untrusted sphere vulnerabilityIn Eclipse Theia versions prior to 1.71.0, the AI chat agent processed workspace file and directory names as part of its prompt context without disti…EPSS 0.51%8.1CVE-2019-17636Eclipse theia insufficient verification of data authenticity vulnerabilityIn Eclipse Theia versions 0.3.9 through 0.15.0, one of the default pre-packaged Theia extensions is "Mini-Browser", published as "@theia/mini-browser…EPSS 0.60%

Source: NIST National Vulnerability Database (record CVE-2026-61891), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.