CVE-2026-12609

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	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

Configurations

Configuration 1 (hide)

cpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-08-05 11:16

Updated : 2026-08-07 20:23

NVD link : CVE-2026-12609

Mitre link : CVE-2026-12609

CVE.ORG link : CVE-2026-12609

JSON object : View

Products Affected

eclipse

theia

CWE

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

{"id": "CVE-2026-12609", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"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"}}], "cvssMetricV31": [{"type": "Secondary", "source": "emo@eclipse.org", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "affected": [{"source": "emo@eclipse.org", "affectedData": [{"vendor": "Eclipse Foundation", "product": "Eclipse Theia", "versions": [{"status": "affected", "version": "1.66.0", "lessThan": "1.74.0", "versionType": "semver"}], "defaultStatus": "unaffected"}]}], "published": "2026-08-05T11:16:24.080", "references": [{"url": "https://github.com/eclipse-theia/theia/security/advisories/GHSA-qmm6-p8q4-2g48", "tags": ["Broken Link"], "source": "emo@eclipse.org"}, {"url": "https://gitlab.eclipse.org/security/cve-assignment/-/work_items/133", "tags": ["Vendor Advisory"], "source": "emo@eclipse.org"}, {"url": "https://gitlab.eclipse.org/security/vulnerability-reports/-/issues/524", "tags": ["Issue Tracking", "Mitigation", "Vendor Advisory"], "source": "emo@eclipse.org"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "emo@eclipse.org", "description": [{"lang": "en", "value": "CWE-22"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-08-07T20:23:46.517", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:eclipse:theia:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "80478E2F-D9E2-4668-86CF-67913770E0AC", "versionEndExcluding": "1.74.0", "versionStartIncluding": "1.66.0"}], "operator": "OR"}]}], "sourceIdentifier": "emo@eclipse.org"}