{"id":"CVE-2026-10054","aliases":["GHSA-78g8-vm3p-97c6"],"url":"https://o3.security/vulnerability/CVE-2026-10054","summary":null,"details":"In affected versions of Eclipse Theia (1.8.1 and later), the browser backend exposes privileged terminal RPC over WebSocket (/services/shell-terminal, /services/terminals/:id) without service-level authentication.\n\n\n\n\nWebSocket origin validation in @theia/core is fail-open: connections are accepted when the Origin header is missing or when no THEIA_HOSTS allowlist is configured (the default). The Socket.IO integration additionally replaces the real Origin header with a client-supplied fix-origin header that an attacker can control or omit.\n\n\n\n\nAs a result, a foreign-origin web page visited by a user with a running Theia instance can open the /services WebSocket namespace, invoke terminal creation, attach to the resulting terminal data channel, execute arbitrary OS commands, and read their output. This affects both local developer setups (drive-by attack) and hosted or tunneled deployments without strong external authentication.\n\n\n\n\nA fix is in development that enforces same-origin validation by default, removes trust in the fix-origin header, gates HTTP and WebSocket access on a SameSite=Strict; HttpOnly connection-token cookie, and sanitizes shell terminal creation options.","published":"2026-07-03T10:11:32.446Z","modified":"2026-08-12T03:51:25.599255892Z","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},"epss":{"score":0.00219,"percentile":0.12612,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://gitlab.eclipse.org/security/vulnerability-reports/-/work_items/376"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10054.json"},{"type":"ADVISORY","url":"https://github.com/eclipse-theia/theia/security/advisories/GHSA-78g8-vm3p-97c6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-10054"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:25.599255892Z"}}