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.

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Solution

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History

Thu, 26 Mar 2026 21:15:00 +0000

Type Values Removed Values Added
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.
Title Outline has a rate limit bypass that allows brute force of email login OTP
Weaknesses CWE-307
References
Metrics cvssV4_0

{'score': 9.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-26T20:56:37.818Z

Reserved: 2026-03-23T14:24:11.619Z

Link: CVE-2026-33640

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2026-03-26T21:17:07.637

Modified: 2026-03-26T21:17:07.637

Link: CVE-2026-33640

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses