[Release-4.22] OCPBUGS-87167: Strip X-SSL-* headers for plain HTTP

[MrSanketkumar]

Vulnerability: CVE-2026-46579 - mTLS client certificate spoofing via HTTP header injection

Fix: Prevents unauthenticated spoofing of mutual TLS client identities by stripping X-SSL-Client-* headers from HTTP requests before they reach backends.

Changes:

• Adds `ROUTER_MUTUAL_TLS_HEADER_FILTER` environment variable (default: `true`)
• Strips all 12 X-SSL headers in HTTP frontends: `public`, `fe_sni`, `fe_no_sni`
• Secure by default - header stripping enabled unless explicitly disabled

Cherry-picked from: d180c82

Summary by CodeRabbit

• Bug Fixes
  • Added security filtering for inbound TLS identity headers across HTTP and HTTPS traffic flows. This prevents potential header spoofing and is enabled by default, with an option to disable via the ROUTER_MUTUAL_TLS_HEADER_FILTER environment variable if needed.

[coderabbitai]

Walkthrough

This PR adds security-focused mutual-TLS header filtering to the HAProxy router configuration. The change conditionally strips inbound X-SSL and related identity headers across all three HTTP and HTTPS frontends to prevent client-side header spoofing, controlled by the ROUTER_MUTUAL_TLS_HEADER_FILTER environment variable (enabled by default).

Changes

Mutual-TLS Header Spoofing Prevention

Layer / File(s)	Summary
Conditional header deletion across HTTP and HTTPS frontends images/router/haproxy/conf/haproxy-config.template	Plain HTTP frontend public, TLS SNI (frontend fe_sni), and TLS no-SNI (frontend fe_no_sni) frontends each gain conditional http-request del-header directives that strip X-SSL-* and X-SSL-Issuer headers when ROUTER_MUTUAL_TLS_HEADER_FILTER is enabled (default), preventing client-side header spoofing before routing logic executes.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• openshift/router#787: Both PRs modify images/router/haproxy/conf/haproxy-config.template to conditionally http-request del-header mutual-TLS spoofing headers (X-SSL/X-SSL-Client-* and X-SSL-Issuer) in the same HAProxy frontends (public, fe_sni, fe_no_sni) under ROUTER_MUTUAL_TLS_HEADER_FILTER.

Suggested reviewers

• frobware

🚥 Pre-merge checks | ✅ 15

✅ Passed checks (15 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Stable And Deterministic Test Names	✅ Passed	This repository does not use Ginkgo testing framework. All test files use Go's standard testing.T framework. The check is not applicable to this codebase.
Test Structure And Quality	✅ Passed	The PR modifies the HAProxy template file to add header stripping logic; no Ginkgo tests exist in the codebase, making the check not applicable.
Microshift Test Compatibility	✅ Passed	No Ginkgo e2e tests were added. All new test files use standard Go testing framework (func Test*). MicroShift compatibility check is not applicable.
Single Node Openshift (Sno) Test Compatibility	✅ Passed	No Ginkgo e2e tests added. All 31 test files are standard Go unit tests with zero Ginkgo imports. PR modifies HAProxy config for CVE-2026-46579, not tests.
Topology-Aware Scheduling Compatibility	✅ Passed	PR modifies only HAProxy config template to strip X-SSL headers. No Kubernetes deployment manifests, controllers, or pod scheduling constraints were modified.
Ote Binary Stdout Contract	✅ Passed	This is the OpenShift router production binary, not an OTE test binary. The OTE Binary Stdout Contract check is not applicable to production routers.
Ipv6 And Disconnected Network Test Compatibility	✅ Passed	This PR does not add any Ginkgo e2e tests. It only modifies the HAProxy config template file. The custom check is not applicable.
No-Weak-Crypto	✅ Passed	PR only modifies HAProxy configuration template to add HTTP header deletion rules; no weak cryptography, custom crypto implementations, or secret comparisons introduced.
Container-Privileges	✅ Passed	PR modifies HAProxy config for security hardening; deploy/router.yaml only adds hostNetwork: true (standard requirement). No privileged containers, SYS_ADMIN, or allowPrivilegeEscalation settings.
No-Sensitive-Data-In-Logs	✅ Passed	PR adds header deletion (not logging) to prevent mTLS spoofing. No new logging statements expose sensitive X-SSL-Client-* headers; headers deleted via http-request rules before capture/logging.
Title check	✅ Passed	The title clearly describes the main change: stripping X-SSL-* headers for plain HTTP as part of a security fix for CVE-2026-46579, and correctly identifies the release branch target.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[openshift-ci-robot]

@MrSanketkumar: This pull request references Jira Issue OCPBUGS-87167, which is invalid:

• release note text must be set and not match the template OR release note type must be set to "Release Note Not Required". For more information you can reference the OpenShift Bug Process.
• expected dependent Jira Issue OCPBUGS-87205 to be in one of the following states: MODIFIED, ON_QA, VERIFIED, but it is Closed (Done) instead
• expected dependent Jira Issue OCPBUGS-87205 to target a version in 5.0.0, but it targets "5.0" instead

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

Details

In response to this:

Vulnerability: CVE-2026-46579 - mTLS client certificate spoofing via HTTP header injection

Fix: Prevents unauthenticated spoofing of mutual TLS client identities by stripping X-SSL-Client-* headers from HTTP requests before they reach backends.

Changes:

• Adds `ROUTER_MUTUAL_TLS_HEADER_FILTER` environment variable (default: `true`)
• Strips all 12 X-SSL headers in HTTP frontends: `public`, `fe_sni`, `fe_no_sni`
• Secure by default - header stripping enabled unless explicitly disabled

Cherry-picked from: d180c82

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[openshift-ci]

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[MrSanketkumar]

@coderabbitai review

[coderabbitai]

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