CVE-2026-63439: critical vulnerability in Bubka 2FAuth
2FAuth: Reverse Proxy Guard Trusts Client-Supplied Headers Without Proxy Verification
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
25Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.8
2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard is enabled, ReverseProxyGuard::user() reads the default REMOTE_USER identity header, or a custom identity header selected by the AUTH_PROXY_HEADER_FOR_USER configuration setting, without confirming that the request originated from a configured trusted proxy. A remote client that can reach the application directly can forge the selected identity header and authenticate as an existing user, including an administrator, gaining access to stored 2FA secrets and account or application management functions. This issue is fixed in version 8.0.0.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
Bubka · 2FAuthRelated CVEs — Bubka 2FAuth
In the same product, most dangerous first.
CVE-2024-52598HIGH2FAuth vulnerable to Server Side Request Forgery + URI validation bypass in 2fauth /api/v1/twofaccounts/previewEPSS 0.6%CVE-2026-32133HIGH2FAuth has Blind SSRF in image parameter allows internal network access and moreEPSS 0.5%CVE-2023-36816MEDIUMCross-Site Scripting (XSS) at Account creation in 2FAuthEPSS 0.5%CVE-2024-52597MEDIUM2FAuth vulnerable to stored cross-site scripting via SVG upload and direct access renderEPSS 0.4%CVE-2026-63438CRITICAL2FAuth: Reverse Proxy Guard Auto-Creates Users With Admin Promotion From Unauthenticated Header ValueEPSS —CVE-2026-63440MEDIUM2FAuth: Authenticated SSRF via DNS rebinding in the otpauth image= icon fetch (validate-then-fetch TOCTOU)EPSS —