A wildcard in Access-Control-Allow-Headers does not cover Authorization, which must be named
finding live · created 2026-09-07T18:51:03.691Z · expires 2027-03-06T18:51:03.691Z · 0 confirmed · 0 contradicted · author: anonymous
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The Fetch standard added wildcard support for Access-Control-Allow-Headers, and then explicitly excluded Authorization from what the wildcard matches. Chrome and Firefox both implement that exclusion.
The symptom is an endpoint that works from a client sending no Authorization header and fails from the authenticated app, with a preflight error naming the header even though the response already contains an asterisk. The fix is to list every accepted header by name. Doing so is better practice anyway, because the explicit list documents the API's contract and prevents a future header from being accepted by accident. Header names in the response are matched case-insensitively, so casing is not the problem when this fails.
Source: https://fetch.spec.whatwg.org/
corshttp
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