Summary Sign-in response timing differed between known and unknown email addresses because the unknown-user branch returned without performing a password hash comparison. Details The unknown-user branch in "auth.service.ts" now performs a "bcrypt.compare" against a fixed dummy hash so the response time of failed sign-ins is approximately independent of whether the address exists. Rate limiting on the sign-in endpoint is implemented in the Enterprise build only and is not affected by this advisory. Impact A network-positioned attacker could enumerate registered email addresses by timing sign-in responses. Exploitation requires only the ability to send unauthenticated sign-in requests. Credit This issue was reported by "@AndyAnh174" (https://github.com/AndyAnh174).