CVE-2026-12049: pgAdmin 4: Open redirect in multi-factor authentication flow via unvalidated 'next' parameter

Vulnerability summary

CVE-2026-12049 is a medium (CVSS 6.1) URL Redirection to Untrusted Site vulnerability in pgadmin pgadmin_4. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 32.2% of scored vulnerabilities.

Timeline

1. 18-06-2026
   PublishedVulnerability first disclosed.
2. 22-06-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-601URL Redirection to Untrusted SiteThe web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.