CVE-2021-21392

Open redirect via transitional IPv6 addresses on dual-stack networks

Severity Score

6.3

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 requests to user provided domains were not restricted to external IP addresses when transitional IPv6 addresses were used. Outbound requests to federation, identity servers, when calculating the key validity for third-party invite events, sending push notifications, and generating URL previews are affected. This could cause Synapse to make requests to internal infrastructure on dual-stack networks. See referenced GitHub security advisory for details and workarounds.

Synapse es un servidor doméstico de referencia de Matrix escrito en python (paquete pypi matrix-synapse). Matrix es un ecosistema para VoIP y mensajería instantánea federada abierta. En Synapse, versiones anteriores a 1.28.0, las peticiones a los dominios proporcionados por el usuario no estaban restringidas a direcciones IP externas cuando se usaban direcciones IPv6 de transición. Las peticiones salientes a la federación, los servidores de identidad, al calcular la validez de la clave para eventos de invitación de terceros, el envío de notificaciones push y la generación de vistas previas de URL están afectadas. Esto podría causar que Synapse realice peticiones a la infraestructura interna en redes de doble pila. Consulte el aviso de seguridad de GitHub al que se hace referencia para obtener detalles y soluciones

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

Medium

Authentication

Single

Confidentiality

Partial

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2020-12-22 CVE Reserved
2021-04-12 CVE Published
2023-03-08 EPSS Updated
2024-08-03 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

CAPEC

References (4)

URL	Tag	Source
https://pypi.org/project/matrix-synapse	Product

URL	Date	SRC

URL	Date	SRC
https://github.com/matrix-org/synapse/pull/9240	2023-11-07
https://github.com/matrix-org/synapse/security/advisories/GHSA-5wrh-4jwv-5w78	2023-11-07

URL	Date	SRC
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY	2023-11-07

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Matrix Search vendor "Matrix"		Synapse Search vendor "Matrix" for product "Synapse"				< 1.28.0 Search vendor "Matrix" for product "Synapse" and version " < 1.28.0"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				34 Search vendor "Fedoraproject" for product "Fedora" and version "34"		-		Affected