Auth bypass in Web-Infra-Dev Midscene
CVE-2026-59804
Midscene Bridge Server through 1.10.3, fixed in commit 86f4118, contains a missing authentication and CORS misconfiguration vulnerability that allows unauthenticated remote attackers to hijack active bridge sessions by opening a cross-origin WebSocket connection to the local Socket.IO server, which performs no Origin header validation and requires no authentication token. Attackers can connect from any web page visited by the victim to seize the single-client slot, intercept and inject automation commands, exfiltrate command-payload data, or unconditionally terminate the server by supplying the MIDSCENE_BRIDGE_SIGNAL_KILL query parameter.
Vulnerability class: Broken Authentication
EPSS: 0.002 (11.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.
Affected products
- Web-infra-dev Midscene — versions 0, 86f4118d1d847041c63d79e347e08c87c3f1a882
Weakness classification (CWE)
References
- disclosure@vulncheck.com (technical-description, exploit)
- disclosure@vulncheck.com (issue-tracking)
- disclosure@vulncheck.com (patch)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-59804?
- CVE-2026-59804 is a medium-severity vulnerability in Web-Infra-Dev Midscene, classified under Missing Authentication for Critical Function. CVSS score: 6.8/10. Published 2026-07-08.
- How severe is CVE-2026-59804?
- Medium severity. CVSS v3 base score is 6.8 out of 10.