OAuth2 Token Leakage in Curl during HTTP(S) Transfers

CVE-2026-3783

What is CVE-2026-3783?

A vulnerability exists in Curl where OAuth2 bearer tokens can be inadvertently exposed during HTTP(S) transfers if a redirect occurs. When a request is redirected to a second URL, the bearer token from the initial request can be leaked to the new hostname under certain conditions. Specifically, if the destination hostname is listed in the .netrc file of the user with relevant machine or default keywords, Curl incorrectly sends the bearer token intended for the first host to the second host, potentially compromising sensitive authentication information.

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