pgAdmin 4: Open redirect in multi-factor authentication flow via unvalidated 'next' parameter

Summary

Open redirect in pgAdmin 4's multi-factor authentication flow. The MFA validate and register endpoints honoured the user-supplied 'next' query/form parameter without confirming the target pointed back inside pgAdmin, so an authenticated victim who clicked /mfa/validate?next=<external> -- a link typically delivered by phishing -- would be sent to an attacker-controlled host directly out of the trusted auth flow. The defect is a trusted-domain redirect, not a privilege bypass: the attacker gains no read/write access to pgAdmin or the victim's database, but the redirect launders the attacker's destination through pgAdmin's URL, which raises the success rate of credential-phishing follow-on against the victim. Fix introduces a same-origin _is_safe_redirect_url helper and gates every MFA redirect that consumes user-supplied 'next' values through it. The helper allows only relative paths and absolute URLs whose scheme is http(s) and whose host matches the current request host; it rejects external hosts in absolute and protocol-relative form, non-http schemes (javascript:, data:, mailto:), userinfo tricks (http://localhost@attacker/), and backslash variants that some browsers normalize to forward slashes. Unsafe targets fall back to the internal browser index. A dedicated regression test exercises each accept/reject category and the original reporter PoC. This issue affects pgAdmin 4: from 6.0 before 9.16.

Timeline

1. Jun 18, 2026, 11:37 PM UTCCVE published
2. Jun 22, 2026, 2:39 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Jun 22, 2026, 2:39 PM UTCRecord last updated

Affected versions

• pgadmin.org pgAdmin 4

  From 6.0 · fixed in 9.16

References 2