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fix(identity): find the pending 2fa cookie by better-auth's own cookie name - #404
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…e name
Over HTTPS better-auth names the pending challenge cookie
`__Secure-better-auth.two_factor`, which the exact match on
`better-auth.two_factor` never found. Verify then rejected a code better-auth
had already accepted, skipped the lockout count, and keyed every pending
attempt on the shared anonymous rate-limit bucket.
Derive the name from `createAuthCookie('two_factor')` on the auth context so
the cookie prefix and secure prefix match what the two-factor plugin sets,
keeping the exact-name match against look-alike cookies.
okapitula
requested review from
jakubfilinger-b,
klaudia-blazyczek-blurify,
marek-chmielowski-blurify,
mp-blurify and
zaxovaiko
as code owners
November 5, 2026 17:13
okapitula
enabled auto-merge
November 5, 2026 17:55
jakubfilinger-b
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Nov 6, 2026
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The cookie lookup now follows Better Auth’s configured cookie name, including the HTTPS prefix. The regression tests cover verification and rate limiting.
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Summary
Why
The lookup matched
better-auth.two_factorexactly. Over HTTPS better-auth sets the cookie as__Secure-better-auth.two_factor, so the lookup found nothing:POST /identity/2fa/verifyanswered 401Invalid two-factor challengeafter better-auth had already accepted the code, the failed-attempt lockout was never counted, and every pending verify shared theverify2fa:anonymousrate-limit bucket. Tests run over plain HTTP, so they never saw the prefixed name.The name now comes from
createAuthCookie('two_factor')on the auth context, which applies the configured cookie prefix and the__Secure-prefix the same way the two-factor plugin does when it sets the cookie. The exact-name match stays, so a look-alike*.two_factorcookie still cannot change the challenge identity or the rate-limit key.Alternatives considered
better-auth.two_factorand__Secure-better-auth.two_factor: still breaks under a customcookiePrefixor a per-cookie name override..two_factorsuffix match: reopens the junk-cookie rate-limit churn the exact match closed.Risks
None. Plain-HTTP deployments resolve the same name as before.