outpost/proxy: fix double host sent on token introspection

[rissson]

Details

closes #25226

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Checklist

• The project has been linted, built, and tested (make all)
• The documentation has been updated and formatted (make docs)

[netlify]

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[codecov]

Codecov Report

❌ Patch coverage is 93.02326% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.52%. Comparing base (16047ba) to head (4a0b876).
⚠️ Report is 8 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/outpost/proxy/backchannel.rs	93.02%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25234      +/-   ##
==========================================
+ Coverage   91.35%   91.52%   +0.17%     
==========================================
  Files        1151     1151              
  Lines       73091    73125      +34     
  Branches     3889     3923      +34     
==========================================
+ Hits        66769    66931     +162     
+ Misses       6286     6158     -128     
  Partials       36       36              

Flag	Coverage Δ
conformance	34.49% <ø> (+0.44%)	⬆️
e2e	39.15% <ø> (+2.26%)	⬆️
integration	31.04% <ø> (-0.04%)	⬇️
rust	39.73% <93.02%> (+0.52%)	⬆️
unit	93.20% <ø> (+9.24%)	⬆️
unit-migrate	93.21% <ø> (+10.69%)	⬆️

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[github-actions]

authentik PR Installation instructions

Instructions for docker-compose

Add the following block to your .env file:

AUTHENTIK_IMAGE=ghcr.io/goauthentik/dev-server
AUTHENTIK_TAG=gh-4a0b876066d99a2dcc4747eb0c8abb16d0893188
AUTHENTIK_OUTPOSTS__CONTAINER_IMAGE_BASE=ghcr.io/goauthentik/dev-%(type)s:gh-%(build_hash)s

Afterwards, run the upgrade commands from the latest release notes.

Instructions for Kubernetes

Add the following block to your values.yml file:

authentik:
    outposts:
        container_image_base: ghcr.io/goauthentik/dev-%(type)s:gh-%(build_hash)s
global:
    image:
        repository: ghcr.io/goauthentik/dev-server
        tag: gh-4a0b876066d99a2dcc4747eb0c8abb16d0893188

Afterwards, run the upgrade commands from the latest release notes.

[authentik-cherry-pick]

🍒 Cherry-pick to version-2026.8 created: #25245