CrowdSecLive Exploit Tracker
Limited ExploitationCVE-2026-12609Public Exploit

Eclipse Theia - Path Traversal (CVE-2026-12609)

PublishedAug 5, 2026
First SeenN/A
Last Seen
Reported
CVSS7.5
EF
Eclipse FoundationEclipse Theia
web_application

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.

psychologyCrowdSec Analysis

CVE-2026-12609 is a high-severity path traversal vulnerability in Eclipse Theia versions 1.66.0 through 1.73.1. An unauthenticated network attacker can use encoded directory traversal sequences to escape a plugin’s directory and retrieve files readable by the Theia backend, potentially exposing sensitive information.

CrowdSec has been tracking this vulnerability and its exploits since 20th of October 2026.

CrowdSec has not observed any significant exploitation activity targeting CVE-2026-12609 across its network. As a result, no community-driven trend analysis is available for this vulnerability at this time.

Attackers target /hostedPlugin/<pluginId>/ (the template uses the built-in vscode_bat plugin) with encoded path-traversal sequences to escape the plugin directory and read files accessible to the Eclipse Theia backend. The template probes for /etc/passwd to confirm successful unauthenticated file disclosure.

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EventDate
CVE Published2026-08-05
Rule Released2026-10-20

Related Weaknesses

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

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External References