fix(cloudflare/worker): don't merge query params into external redirects#288
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The Cloudflare worker proxies the upstream Lambda's redirect responses back to the browser. Previously it merged the original request's query string into every redirect target, including external ones like S3 presigned URLs. This broke any service that issues a 3xx to an S3 presigned URL (e.g. storage-service): the extra param (e.g. ?secret=...) changes the canonical query string, so X-Amz-Signature no longer matches and S3 returns "SignatureDoesNotMatch". It also leaked the original request's secrets to whatever third party we redirected to. Move the query-merge inside the same `target.hostname === overrideHost` branch as the hostname rewrite — same-upstream redirects still merge, external redirects pass through untouched.
smecsia
approved these changes
May 21, 2026
Semgrep Scan ResultsRepository:
Scanned at 2026-05-21 20:35 UTC |
Security Scan ResultsRepository:
Scanned at 2026-05-21 20:36 UTC |
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The Cloudflare worker proxies the upstream Lambda's redirect responses back to the browser. Previously it merged the original request's query string into every redirect target, including external ones like S3 presigned URLs.
This broke any service that issues a 3xx to an S3 presigned URL (e.g. storage-service): the extra param (e.g. ?secret=...) changes the canonical query string, so X-Amz-Signature no longer matches and S3 returns "SignatureDoesNotMatch". It also leaked the original request's secrets to whatever third party we redirected to.
Move the query-merge inside the same
target.hostname === overrideHostbranch as the hostname rewrite — same-upstream redirects still merge, external redirects pass through untouched.