CVE-2026-33640

Critical

Description

Outline is a service that allows for collaborative documentation. Outline implements an Email OTP login flow for users not associated with an Identity Provider. Starting in version 0.86.0 and prior to version 1.6.0, Outline does not invalidate OTP codes based on amount or frequency of invalid submissions, rather it relies on the rate limiter to restrict attempts. Consequently, identified bypasses in the rate limiter permit unrestricted OTP code submissions within the codes lifetime. This allows attackers to perform brute force attacks which enable account takeover. Version 1.6.0 fixes the issue.

SeverityCritical
CVSS9.8
Exploit probability—
ProductOutline
PublishedMar 26, 2026
First seenMar 26, 2026
Weakness typeCWE-307CWE-307

How to fix

Update
  • getoutline outline1.6.0 or later

Affected products

ProductAffected versionsFixed in
getoutline outline0.86.0 ≤ v < 1.6.01.6.0

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.