Path Traversal in Eclipse Theia (CVE-2026-61891)
Summary
Path traversal in Eclipse Theia (CVE-2026-61891). Confidential information can be exposed externally. Exploitable via GET /file.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-61891 has been found in Eclipse Theia.
Attackers can target a specific entry point like GET /file over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Eclipse Theia CVE-2026-61891" on the vendor's site.
CVE-2026-61891 (Eclipse Theia) — CWE-22 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: GET /file / GET /files/ / PUT /files/ / ElectronSecurityToken
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Path traversal (CWE-22) exists in Eclipse Theia. Attackers reach the vulnerable code path via GET /file without authentication.
Check the vendor advisory for the affected versions of Eclipse Theia. Attack surface: GET /file / GET /files/ / PUT /files/ / ElectronSecurityToken.
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual GET /file requests with malformed payloads or SQL meta-characters. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Eclipse Theia を使っているサービスとバージョンを洗い出す。
-
2Hunt for indicators of compromise detect
grep 'GET /file' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
GET /fileへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Post-deployment verification verify
Replay attack against GET /file on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
References
- patch emo@eclipse.org
- patch emo@eclipse.org
- web emo@eclipse.org
- web nvd.nist.gov
- web github.com