CVE-2026-12609: theia from 1.66.0 (inclusive), before 1.74.0 (exclusive); +1 more affected products

Affected technology

theia · from 1.66.0 (inclusive), before 1.74.0 (exclusive)
eclipse

Eclipse Theia · 1.66.0 to before 1.74.0
Eclipse Foundation

Description’s affected range: versions 1.66.0 and up until including 1.73.1

Component: Not specified by the source

Attack conditions (Vendor/CNA, CVSS 3.1): Network (remote) · No privileges required · No user interaction required

What an attacker can do

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. Vendor/CNA’s CVSS 3.1 assessment (base score 7.5/10) rates confidentiality impact as high; integrity and availability impact as none.