A flaw was found in the Conditional OTP authenticator of Keycloak, an identity and access management solution. The issue occurs when the system evaluates specific HTTP headers to determine if a one-time password (OTP) should be skipped, but fails to verify if those headers came from a trusted source. This could allow an attacker who already has a user's password to bypass the second-factor authentication by providing a specially crafted header in their request.
Credits
Red Hat would like to thank Paul Bottinelli (Trail of Bits in collaboration with OpenAI) for reporting this issue.