fix(coderd): harden oauth2 redirect validation (#27274) - #27464
#27464Merged
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fix(coderd): harden oauth2 redirect validation (#27274)#27464
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aslilac
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DanielleMaywood,
Emyrk and
jdomeracki-coder
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July 23, 2026 18:18
Closes DEVEX-604 Hardens `redirect` URL handling in the OAuth2/OIDC/external-auth callback flows so redirects are always reduced to a safe, relative path local to the application. Previously a redirect value with an opaque scheme (e.g. `javascript:...`) or a path with multiple leading slashes (e.g. `///evil.com`) could survive sanitization mostly intact. Also de-duplicates the previously copy-pasted `uriFromURL` helper (now exported `httpmw.URIFromURL`) so there's a single implementation shared by `coderd/userauth.go`, `coderd/externalauth.go`, and `coderd/httpmw/oauth2.go`. <details> <summary>Context</summary> Addresses a low-severity finding reported via a pentest disclosure: the redirect sanitizer used `url.Parse(...).RequestURI()`, which doesn't reject non-hierarchical (opaque) URLs and doesn't collapse extra leading slashes, so crafted `redirect` values could partially survive sanitization. </details> This PR was authored by a Coder Agent on behalf of @aslilac. (cherry picked from commit 2f87991)
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Emyrk
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Jul 23, 2026
mtojek
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Backport of #27274
Original PR: #27274 — fix(coderd): harden oauth2 redirect validation
Merge commit: 2f87991
Requested by: @aslilac