CVE-2026-33640

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.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/outline/outline/releases/tag/v1.6.0	Release Notes
https://github.com/outline/outline/security/advisories/GHSA-cwhc-53hw-qqx6	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:getoutline:outline:*:*:*:*:*:*:*:*

History

31 Mar 2026, 01:42

Type	Values Removed	Values Added
References	~~() https://github.com/outline/outline/releases/tag/v1.6.0 -~~	() https://github.com/outline/outline/releases/tag/v1.6.0 - Release Notes
References	~~() https://github.com/outline/outline/security/advisories/GHSA-cwhc-53hw-qqx6 -~~	() https://github.com/outline/outline/security/advisories/GHSA-cwhc-53hw-qqx6 - Exploit, Vendor Advisory
First Time		Getoutline Getoutline outline
CPE		cpe:2.3:a:getoutline:outline::::::::
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.8

Information

Published : 2026-03-26 21:17

Updated : 2026-03-31 01:42

NVD link : CVE-2026-33640

Mitre link : CVE-2026-33640

CVE.ORG link : CVE-2026-33640

JSON object : View

Products Affected

getoutline

outline

CWE

CWE-307

Improper Restriction of Excessive Authentication Attempts

{"id": "CVE-2026-33640", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 9.1, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "valueDensity": "NOT_DEFINED", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2026-03-26T21:17:07.637", "references": [{"url": "https://github.com/outline/outline/releases/tag/v1.6.0", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/outline/outline/security/advisories/GHSA-cwhc-53hw-qqx6", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-307"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Outline es un servicio que permite la documentaci\u00f3n colaborativa. Outline implementa un flujo de inicio de sesi\u00f3n con OTP por correo electr\u00f3nico para usuarios no asociados con un Proveedor de Identidad. A partir de la versi\u00f3n 0.86.0 y antes de la versi\u00f3n 1.6.0, Outline no invalida los c\u00f3digos OTP bas\u00e1ndose en la cantidad o frecuencia de env\u00edos inv\u00e1lidos, sino que se basa en el limitador de velocidad para restringir los intentos. En consecuencia, los bypasses identificados en el limitador de velocidad permiten el env\u00edo ilimitado de c\u00f3digos OTP dentro de la vida \u00fatil de los c\u00f3digos. Esto permite a los atacantes realizar ataques de fuerza bruta que posibilitan la toma de control de cuentas. La versi\u00f3n 1.6.0 corrige el problema."}], "lastModified": "2026-03-31T01:42:34.940", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:getoutline:outline:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "618371C5-39DB-422A-9E34-034A84D32E3A", "versionEndExcluding": "1.6.0", "versionStartIncluding": "0.86.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}