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fix: normalize allowlist headers when building the allowlist map #6481

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Merged
javiermolinar merged 2 commits into from
Feb 17, 2026
Merged

fix: normalize allowlist headers when building the allowlist map #6481

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3c743e4
fix: normalize allowlist headers when building the allowlist map
javiermolinar Feb 17, 2026
855fb26
add more tests and changelog
javiermolinar Feb 17, 2026
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
* [BUGFIX] generator: fix dimension_mappings and target_info_excluded_dimensions being unconditionally overwritten even when overrides were nil [#6390](https://github.com/grafana/tempo/pull/6390) (@carles-grafana)
* [BUGFIX] generator: fix panic when `write_relabel_configs` is configured on remote write endpoints [#6396](https://github.com/grafana/tempo/pull/6396) (@carles-grafana)
* [BUGFIX] fix: reload span_name_sanitization overrides during runtime [#6435](https://github.com/grafana/tempo/pull/6435) (@electron0zero)
* [BUGFIX] fix: normalize allowlist headers when building the allowlist map [#6481](https://github.com/grafana/tempo/pull/6481) (@javiermolinar)

### 3.0 Cleanup

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6 changes: 4 additions & 2 deletions modules/frontend/pipeline/async_strip_headers_middleware.go
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@@ -1,6 +1,8 @@
package pipeline

import (
"net/http"

"github.com/grafana/tempo/modules/frontend/combiner"
)

Expand All @@ -17,7 +19,7 @@ func NewStripHeadersWare(allowList []string) AsyncMiddleware[combiner.PipelineRe
// build allowed map
allowed := make(map[string]struct{}, len(allowList))
for _, header := range allowList {
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allowed[header] = struct{}{}
allowed[http.CanonicalHeaderKey(header)] = struct{}{}
}

return AsyncMiddlewareFunc[combiner.PipelineResponse](func(next AsyncRoundTripper[combiner.PipelineResponse]) AsyncRoundTripper[combiner.PipelineResponse] {
Expand All @@ -36,7 +38,7 @@ func (c stripHeadersWare) RoundTrip(req Request) (Responses[combiner.PipelineRes
} else {
// clear out headers not in allow list
for header := range httpReq.Header {
if _, ok := c.allowed[header]; !ok {
if _, ok := c.allowed[http.CanonicalHeaderKey(header)]; !ok {
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delete(httpReq.Header, header)
}
}
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18 changes: 18 additions & 0 deletions modules/frontend/pipeline/async_strip_headers_middleware_test.go
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Expand Up @@ -29,6 +29,24 @@ func TestStripHeaders(t *testing.T) {
headers: map[string][]string{"header1": {"value1"}, "header2": {"value2"}},
expected: map[string][]string{"header1": {"value1"}},
},
{
name: "allow list is case-insensitive",
allow: []string{"x-plugin-id", "AUTHORIZATION"},
headers: map[string][]string{"X-Plugin-Id": {"grafana-assistant"}, "authorization": {"Bearer abc"}, "X-Drop-Me": {"nope"}},
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expected: map[string][]string{"X-Plugin-Id": {"grafana-assistant"}, "authorization": {"Bearer abc"}},
},
{
name: "allow list keeps uppercase non-canonical incoming header",
allow: []string{"x-plugin-id", "AUTHORIZATION"},
headers: map[string][]string{"X-PLUGIN-ID": {"grafana-assistant"}, "authorization": {"Bearer abc"}, "X-Drop-Me": {"nope"}},
expected: map[string][]string{"X-PLUGIN-ID": {"grafana-assistant"}, "authorization": {"Bearer abc"}},
},
{
name: "allow list keeps lowercase non-canonical incoming header",
allow: []string{"x-plugin-id", "AUTHORIZATION"},
headers: map[string][]string{"x-plugin-id": {"grafana-assistant"}, "authorization": {"Bearer abc"}, "X-Drop-Me": {"nope"}},
expected: map[string][]string{"x-plugin-id": {"grafana-assistant"}, "authorization": {"Bearer abc"}},
},
}

for _, tc := range tcs {
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