Reject control characters in local redirect URL validation - #4028
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RedirectUriHelper.IsLocalUrl and the AccountController SignIn/Challenge redirect checks accepted paths containing raw ASCII control characters (e.g. tab/CR/LF). Browsers strip these per the WHATWG URL spec, so a value like "/<tab>/host" resolves to a protocol-relative URL after stripping and was treated as local. Add a HasControlCharacter guard (rejects C0 range and DEL) so the library enforces this independent of the host's ASP.NET Core version. Internal/private helpers only; no public API change. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: e64c3d8c-4f86-4d0b-ac12-0da2e2d44a5b
Combine the AccountController redirect checks, simplify helper documentation, correct the control-character example, and clarify the legacy framework behavior modeled by the tests. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: e64c3d8c-4f86-4d0b-ac12-0da2e2d44a5b
Document that percent-encoded slash checks use case-insensitive hexadecimal comparison as defined by RFC 3986. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: e64c3d8c-4f86-4d0b-ac12-0da2e2d44a5b
Explain the redirect risk in plain language without relying on standards terminology. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: e64c3d8c-4f86-4d0b-ac12-0da2e2d44a5b
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RedirectUriHelper.IsLocalUrl and the AccountController SignIn/Challenge redirect checks accepted paths containing raw ASCII control characters (e.g. tab/CR/LF). Browsers strip these per the WHATWG URL spec, so a value like "//host" resolves to a protocol-relative URL after stripping and was treated as local. Add a HasControlCharacter guard (rejects C0 range and DEL) so the library enforces this independent of the host's ASP.NET Core version. Internal/private helpers only; no public API change.
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