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The Location header for the trailing-slash redirect is built from req.url. Only a leading run of '/' was collapsed, so /\host still produced a protocol relative target in browsers, and a URL made only of slashes made substr throw out_of_range.
gittiver
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Sep 17, 2026
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the use of percent encoded / and \ needs also to be investigated.
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The trailing-slash redirect in routing.h builds Location from req.url, and the fix for GHSA-x6vq-298x-6qgq only collapses a leading run of '/'. A request for /\attacker.example still gets Location: /\attacker.example/, which browsers resolve as //attacker.example/ so the open redirect remains, and a URL made only of slashes makes find_first_not_of return npos so the substr call throws out_of_range and the connection is left without a response. Both redirect sites now strip the leading run of '/' and '' and rebuild the target rooted at a single slash, with the existing redirect test extended to cover both inputs.