CVE-2026-12609
Eclipse Theia Path Traversal Vulnerability
Description
In Eclipse Theia versions 1.66.0 and up until including 1.73.1, the `@theia/plugin-ext` backend exposes the `/hostedPlugin/:pluginId/:path(*)` HTTP endpoint, which resolves the requested file path with `path.resolve(localPath, filePath)` without verifying that the resolved path stays within the plugin's directory. An unauthenticated network attacker can send percent-encoded `../` sequences (`%2e%2e%2f`) that decode into the path parameter and escape the plugin directory, allowing arbitrary files readable by the Theia backend process to be retrieved. Plugin IDs are derived deterministically from a plugin's publisher and name, so built-in plugins serve as reliable anchors that require no prior knowledge of the target system.
INFO
Published Date :
Aug. 5, 2026, 11:16 a.m.
Last Modified :
Aug. 7, 2026, 8:23 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | e51fbebd-6053-4e49-959f-1b94eeb69a2c | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update Eclipse Theia to version 1.74.0 or later.
- Apply relevant security patches for older versions if available.
- Restrict access to the affected endpoint if patching is delayed.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-12609.
| URL | Resource |
|---|---|
| https://github.com/eclipse-theia/theia/security/advisories/GHSA-qmm6-p8q4-2g48 | Broken Link |
| https://gitlab.eclipse.org/security/cve-assignment/-/work_items/133 | Vendor Advisory |
| https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/524 | Issue Tracking Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-12609 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-12609
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-12609 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-12609 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Aug. 07, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:* versions from (including) 1.66.0 up to (excluding) 1.74.0 Added Reference Type Eclipse Foundation: https://github.com/eclipse-theia/theia/security/advisories/GHSA-qmm6-p8q4-2g48 Types: Broken Link Added Reference Type Eclipse Foundation: https://gitlab.eclipse.org/security/cve-assignment/-/work_items/133 Types: Vendor Advisory Added Reference Type Eclipse Foundation: https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/524 Types: Issue Tracking, Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 05, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-12609', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-05T13:03:16.183383Z'} -
New CVE Received by [email protected]
Aug. 05, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Eclipse Foundation', 'product': 'Eclipse Theia', 'versions': [{'status': 'affected', 'version': '1.66.0', 'lessThan': '1.74.0', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added Description In Eclipse Theia versions 1.66.0 and up until including 1.73.1, the `@theia/plugin-ext` backend exposes the `/hostedPlugin/:pluginId/:path(*)` HTTP endpoint, which resolves the requested file path with `path.resolve(localPath, filePath)` without verifying that the resolved path stays within the plugin's directory. An unauthenticated network attacker can send percent-encoded `../` sequences (`%2e%2e%2f`) that decode into the path parameter and escape the plugin directory, allowing arbitrary files readable by the Theia backend process to be retrieved. Plugin IDs are derived deterministically from a plugin's publisher and name, so built-in plugins serve as reliable anchors that require no prior knowledge of the target system. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added CWE CWE-22 Added Reference https://github.com/eclipse-theia/theia/security/advisories/GHSA-qmm6-p8q4-2g48 Added Reference https://gitlab.eclipse.org/security/cve-assignment/-/work_items/133 Added Reference https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/524