Login redirect loop when running behind reverse-proxy #42999

ArthurAttout · 2025-09-26T14:39:04Z

ArthurAttout
Sep 26, 2025

Before reporting an issue

I have read and understood the above terms for submitting issues, and I understand that my issue may be closed without action if I do not follow them.

Area

login/ui

Describe the bug

When trying to log in with the bootstrap admin credentials into an instance of keycloak served behind an Apache2 reverse proxy, the login portal will enter a redirection loop after the credentials have been entered.

The following loop occurs :

The keycloak logs spam the line :

keycloak           | 2025-09-26 14:25:28,118 WARN  [org.keycloak.events] (executor-thread-7) type="REFRESH_TOKEN_ERROR", realmId="ccf276a9-e2ef-4e12-8071-1a563045c3dc", realmName="master", clientId="security-admin-console", userId="null", ipAddress="10.17.130.252", error="invalid_token", reason="Invalid refresh token", grant_type="refresh_token", client_auth_method="client-secret"
keycloak           | 2025-09-26 14:25:28,858 WARN  [org.keycloak.events] (executor-thread-9) type="REFRESH_TOKEN_ERROR", realmId="ccf276a9-e2ef-4e12-8071-1a563045c3dc", realmName="master", clientId="security-admin-console", userId="null", ipAddress="10.17.130.252", error="invalid_token", reason="Invalid refresh token", grant_type="refresh_token", client_auth_method="client-secret"
keycloak           | 2025-09-26 14:25:29,521 WARN  [org.keycloak.events] (executor-thread-7) type="REFRESH_TOKEN_ERROR", realmId="ccf276a9-e2ef-4e12-8071-1a563045c3dc", realmName="master", clientId="security-admin-console", userId="null", ipAddress="10.17.130.252", error="invalid_token", reason="Invalid refresh token", grant_type="refresh_token", client_auth_method="client-secret"

The login portal performed the following request, which resulted in a HTTP 400 :

fetch("https://<REDACTED>/keycloak/realms/master/protocol/openid-connect/token", {
  "headers": {
    "accept": "*/*",
    "accept-language": "fr-FR,fr;q=0.9",
    "cache-control": "no-cache",
    "content-type": "application/x-www-form-urlencoded",
    "pragma": "no-cache",
    "sec-ch-ua": "\"Not;A=Brand\";v=\"99\", \"Google Chrome\";v=\"139\", \"Chromium\";v=\"139\"",
    "sec-ch-ua-mobile": "?0",
    "sec-ch-ua-platform": "\"Windows\"",
    "sec-fetch-dest": "empty",
    "sec-fetch-mode": "cors",
    "sec-fetch-site": "same-origin"
  },
  "body": "grant_type=refresh_token&refresh_token=undefined&client_id=security-admin-console",
  "method": "POST",
  "mode": "cors",
  "credentials": "include"
});

Version

quay.io/keycloak/keycloak:26.3.5

Regression

The issue is a regression

Expected behavior

Entering the bootstrap credentials should open the administration console.

Actual behavior

A login redirect loop occurs.

How to Reproduce?

Using the following Apache2 reverse proxy conf

<VirtualHost *:80>

	LoadModule headers_module /usr/lib/apache2/modules/mod_headers.so

	ServerAdmin webmaster@localhost
	DocumentRoot /var/www

	# enable SSL
	#SSLEngine on
	#SSLCertificateFile /etc/ssl/certs/server.crt
	#SSLCertificateKeyFile /etc/ssl/private/server.key
	#SSLCertificateChainFile /etc/ssl/certs/server_chain.pem

	#enable logging
	ErrorLog ${APACHE_LOG_DIR}/error.log
	CustomLog ${APACHE_LOG_DIR}/access.log combined

	# Configure Reverse Proxy entries
	ProxyPreserveHost On
	RewriteEngine On
		
	 <Location /keycloak>
		RequestHeader set X-Forwarded-Proto "https"
		RequestHeader set X-Forwarded-Host "<REDACTED>"
		RequestHeader set X-Forwarded-Port "443"
		ProxyPass http://keycloak:8080/keycloak/
		ProxyPassReverse http://keycloak:8080/keycloak/
	 </Location>

</VirtualHost>

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

And the following docker-compose.yml for Keycloak

services:
  keycloak:
    image: quay.io/keycloak/keycloak:26.3.5
    container_name: keycloak
    environment:
      - KC_HOST=<REDACTED>
      - KC_BOOTSTRAP_ADMIN_USERNAME=admin
      - KC_BOOTSTRAP_ADMIN_PASSWORD=admin
      - KC_DB=postgres
      - KC_DB_USERNAME=keycloak
      - KC_DB_PASSWORD=keycloak
      - KC_DB_URL_HOST=postgres-keycloak
      - KC_HOSTNAME_STRICT=false
      - KC_HTTP_RELATIVE_PATH=/keycloak
      - KC_HTTP_ENABLED=true #encryption handled by reverse proxy
      #- PROXY_ADDRESS_FORWARDING=true
      - KC_PROXY_HEADERS=xforwarded
      #- KC_PROXY=edge
    command: start-dev


  db:
    image: postgres
    container_name: postgres-keycloak
    restart: always
    shm_size: 128mb
    environment:
      - POSTGRES_PASSWORD=keycloak
      - POSTGRES_USER=keycloak

networks:
  default:
    name: my-network
    external: true

Anything else?

The request to /token which returns 400 is suspicious to me. Using undefined seems odd. However I have absolutely no idea how to track this bug.

The only additional info in the browser console is
An iframe which has both allow-scripts and allow-same-origin for its sandbox attribute can escape its sandboxing.

Answered by shawkins

Sep 29, 2025

Your situation and the screen cap of the request sequence seems similar to #40111 - can you double check if anything is causing keycloak cookies to be lost?

View full answer

shawkins · 2025-09-26T15:21:02Z

shawkins
Sep 26, 2025
Collaborator

Moved to a discussion initially. In most instances something with this description is due to the proxy configuration.

The relevant settings on the Keycloak side:

KC_HOSTNAME_STRICT=false
KC_HTTP_RELATIVE_PATH=/keycloak
KC_HTTP_ENABLED=true #encryption handled by reverse proxy
KC_PROXY_HEADERS=xforwarded

Indicate you are in an edge mode, and there is no fixed Keycloak hostname - which is not recommended.

Using the following Apache2 reverse proxy conf

I don't see encryption being handled by the proxy. That config snippet is showing the port 80 http configuration - but is setting forwarded headers as if the request is coming from https / 443. You should issue a redirect instead.

3 replies

ArthurAttout Sep 29, 2025
Author

I should have specified that my Apache2 server is already behind a load balancer that decrypts SSL communications for me. I'm only handling pure HTTP at my level. I don't manage that load balancer, although I can ensure that Keycloak receives the X-Forwarded-* HTTP headers

shawkins Sep 29, 2025
Collaborator

Have you used hostname-debug to double check what is being seen by the Keycloak server?

ArthurAttout Sep 29, 2025
Author

Yes, retrieved from https://redacted.hostname.hub/keycloak/realms/master/hostname-debug, and everything looks fine to me

URL	Value
Request	https://redacted.hostname.hub/keycloak/realms/master/hostname-debug
Frontend	https://redacted.hostname.hub/keycloak [OK]
Backend	https://redacted.hostname.hub/keycloak/ [OK]
Admin	https://redacted.hostname.hub/keycloak [OK]
Runtime	Value
Server mode	dev [start-dev]
Realm	master
Hostname SPI implementation	V2
Configuration property	Value
hostname	https://redacted.hostname.hub/keycloak
hostname-backchannel-dynamic	true
hostname-strict	false
proxy-headers	xforwarded
http-enabled	true
http-relative-path	/keycloak
http-port	8080
https-port	8443
Header	Value
Host	redacted.hostname.hub
X-Forwarded-For	10.77.111.240, 10.242.23.27
X-Forwarded-Host	redacted.hostname.hub
X-Forwarded-Proto	https

shawkins · 2025-09-29T12:14:26Z

shawkins
Sep 29, 2025
Collaborator

Your situation and the screen cap of the request sequence seems similar to #40111 - can you double check if anything is causing keycloak cookies to be lost?

2 replies

ArthurAttout Sep 29, 2025
Author

According to #40111, the issue disappeared after removing the HttpOnly attribute from the cookies stored for Keycloak.
The browser cookie inspector shows they are all HttpOnly. So Javascript cannot access them (which I suppose is a problem).

It looks like my issue is upstream. Will keep you updated if it's related to the Keycloak config in any means.

ArthurAttout Oct 2, 2025
Author

I confirm this was due to a server somewhere in my upstream, setting an HttpOnly attribute to every Set-Cookie header.

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Login redirect loop when running behind reverse-proxy #42999

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ArthurAttout Sep 26, 2025

Before reporting an issue

Area

Describe the bug

Version

Regression

Expected behavior

Actual behavior

How to Reproduce?

Anything else?

Replies: 2 comments · 5 replies

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shawkins Sep 26, 2025 Collaborator

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ArthurAttout Sep 29, 2025 Author

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Sep 26, 2025

Replies: 2 comments 5 replies

shawkins
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