# CVE-2026-86863: pgAdmin 4 authentication bypass in webserver mode

Source: https://junglewise.ai/threats/cve-2026-86863-pgadmin-4-authentication-bypass-in-webserver-mode  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-17. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-86863 · Severity: critical · CVSS 9.8 · Published 2026-09-17

pgAdmin 4 is a web-based database administration tool. When configured to use webserver authentication (a method to delegate user identity verification to a reverse proxy or web server), an attacker able to reach pgAdmin could bypass authentication by forging HTTP headers, potentially gaining Administrator access without a password. This affects deployments that use webserver authentication mode and rely on it as a security boundary.

## Quick answers

**Is CVE-2026-86863 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86863 being exploited in the wild.

**How severe is CVE-2026-86863?** Critical severity, with a CVSS score of 9.8, published 17 September 2026.

**Which products and versions are affected?** pgAdmin pgAdmin 4 6.2 to 9.17.

**Is there a fix for CVE-2026-86863?** A patch was published on 2026-09-17: Fix available in pgAdmin 4 9.18 and later Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86863 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-86863?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an authentication bypass in pgAdmin 4's webserver authentication source. The WebserverAuthentication.get_user() method attempted to read the authenticated identity from WSGI/CGI environment variables (config.WEBSERVER_REMOTE_USER), but fell back to reading the same variable name directly from HTTP request headers when not found in the environment. Since HTTP request headers are client-controlled, an attacker could supply a forged header to assert any identity, including Administrator accounts. Additionally, certain environment variable names (HTTP_-prefixed or hyphenated) could be populated by inbound headers in WSGI, further lowering the attack bar. The fix requires explicit opt-in for header-based identity (WEBSERVER_REMOTE_USER_FROM_HEADER), validates that the request originates from a trusted proxy (WEBSERVER_TRUSTED_PROXIES), optionally checks a shared secret (WEBSERVER_SHARED_SECRET_HEADER), and adds defensive checks to reject accounts not tagged with 'webserver' auth_source. This vulnerability affects pgAdmin 4 versions 6.2 through 9.17 when webserver authentication is enabled.

## Affected products

- pgAdmin pgAdmin 4 6.2 to 9.17

## Timeline

- 2026-09-17: disclosed
- 2026-09-17: patched: Fix available in pgAdmin 4 9.18 and later