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[release-4.13] OCPBUGS-86710: Strip X-SSL-* headers for plain HTTP #808

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[release-4.13] OCPBUGS-86710: Strip X-SSL-* headers for plain HTTP #808

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53 changes: 53 additions & 0 deletions images/router/haproxy/conf/haproxy-config.template
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,23 @@ frontend public
# Strip off Proxy headers to prevent HTTpoxy (https://httpoxy.org/)
http-request del-header Proxy

# Strip off X-SSL* headers for plain HTTP if not explicitly disabled.
# This prevents unauthenticated spoofing of mutual TLS client identities.
{{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}
http-request del-header X-SSL
http-request del-header X-SSL-Client-CN
http-request del-header X-SSL-Client-DER
http-request del-header X-SSL-Client-DN
http-request del-header X-SSL-Client-NotAfter
http-request del-header X-SSL-Client-NotBefore
http-request del-header X-SSL-Client-SHA1
http-request del-header X-SSL-Client-Serial
http-request del-header X-SSL-Client-Subject
http-request del-header X-SSL-Client-Verify
http-request del-header X-SSL-Client-Version
http-request del-header X-SSL-Issuer
{{- end }}
Comment on lines +228 to +243

@coderabbitai coderabbitai Bot Jun 29, 2026

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🔒 Security & Privacy | 🟠 Major | ⚡ Quick win

Keep the filter enabled on malformed env values.

isTrue(env(..., "true")) is only secure-by-default when the variable is unset. If ROUTER_MUTUAL_TLS_HEADER_FILTER is set to any non-empty typo, env() returns that value and isTrue() falls back to false, which silently disables the CVE mitigation without an explicit opt-out.

Suggested fix 
-  {{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}
+  {{- $mtlsHeaderFilter := firstMatch "(?i:true|false)" (env "ROUTER_MUTUAL_TLS_HEADER_FILTER") "true" }}
+  {{- if isTrue $mtlsHeaderFilter }}

Also applies to: 341-357, 453-469

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@images/router/haproxy/conf/haproxy-config.template` around lines 228 - 243,
The mutual-TLS header stripping in the haproxy-config.template blocks is only
enabled when isTrue(env(..., "true")) evaluates true, which can silently disable
the mitigation for malformed non-empty values. Update the
ROUTER_MUTUAL_TLS_HEADER_FILTER check so the filter stays enabled by default
unless the variable is explicitly set to a recognized false value, and reuse the
same logic in the other matching header-filter sections to keep behavior
consistent.


# DNS labels are case insensitive (RFC 4343), we need to convert the hostname into lowercase
# before matching, or any requests containing uppercase characters will never match.
http-request set-header Host %[req.hdr(Host),lower]
Expand Down Expand Up @@ -321,6 +338,24 @@ frontend fe_sni
# Strip off Proxy headers to prevent HTTpoxy (https://httpoxy.org/)
http-request del-header Proxy

# Strip off X-SSL* headers if not explicitly disabled.
# This prevents unauthenticated spoofing of mutual TLS client identities
# when mutual TLS is not enabled and so the headers are not set below.
{{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}
http-request del-header X-SSL
http-request del-header X-SSL-Client-CN
http-request del-header X-SSL-Client-DER
http-request del-header X-SSL-Client-DN
http-request del-header X-SSL-Client-NotAfter
http-request del-header X-SSL-Client-NotBefore
http-request del-header X-SSL-Client-SHA1
http-request del-header X-SSL-Client-Serial
http-request del-header X-SSL-Client-Subject
http-request del-header X-SSL-Client-Verify
http-request del-header X-SSL-Client-Version
http-request del-header X-SSL-Issuer
{{- end }}

# DNS labels are case insensitive (RFC 4343), we need to convert the hostname into lowercase
# before matching, or any requests containing uppercase characters will never match.
http-request set-header Host %[req.hdr(Host),lower]
Expand Down Expand Up @@ -415,6 +450,24 @@ frontend fe_no_sni
# Strip off Proxy headers to prevent HTTpoxy (https://httpoxy.org/)
http-request del-header Proxy

# Strip off X-SSL* headers if not explicitly disabled.
# This prevents unauthenticated spoofing of mutual TLS client identities
# when mutual TLS is not enabled and so the headers are not set below.
{{- if isTrue (env "ROUTER_MUTUAL_TLS_HEADER_FILTER" "true") }}
http-request del-header X-SSL
http-request del-header X-SSL-Client-CN
http-request del-header X-SSL-Client-DER
http-request del-header X-SSL-Client-DN
http-request del-header X-SSL-Client-NotAfter
http-request del-header X-SSL-Client-NotBefore
http-request del-header X-SSL-Client-SHA1
http-request del-header X-SSL-Client-Serial
http-request del-header X-SSL-Client-Subject
http-request del-header X-SSL-Client-Verify
http-request del-header X-SSL-Client-Version
http-request del-header X-SSL-Issuer
{{- end }}

# DNS labels are case insensitive (RFC 4343), we need to convert the hostname into lowercase
# before matching, or any requests containing uppercase characters will never match.
http-request set-header Host %[req.hdr(Host),lower]
Expand Down