Themisp20

**Name of the Vulnerable Software and Affected Versions** Outline versions 0.86.0 through 1.5.9 **Description** Outline is a service that allows for collaborative documentation. It uses an Email OTP login flow for users not associated with an Identity Provider. Versions of Outline between 0.86.0 and 1.5.9 do not invalidate OTP codes based on the number or frequency of invalid submissions, relying instead on a rate limiter to restrict attempts. Identified bypasses in the rate limiter allow attackers to submit OTP codes without restriction within the codes' lifetime. This enables brute force attacks that can lead to account takeover. **Recommendations** Update to version 1.6.0 or later.