// For flags

CVE-2021-43791

Ineffective expiration validation for invitation links in Zulip

Severity Score

5.3
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

Zulip is an open source group chat application that combines real-time chat with threaded conversations. In affected versions expiration dates on the confirmation objects associated with email invitations were not enforced properly in the new account registration flow. A confirmation link takes a user to the check_prereg_key_and_redirect endpoint, before getting redirected to POST to /accounts/register/. The problem was that validation was happening in the check_prereg_key_and_redirect part and not in /accounts/register/ - meaning that one could submit an expired confirmation key and be able to register. The issue is fixed in Zulip 4.8. There are no known workarounds and users are advised to upgrade as soon as possible.

Zulip es una aplicación de chat de grupo de código abierto que combina el chat en tiempo real con conversaciones en hilos. En las versiones afectadas, las fechas de caducidad de los objetos de confirmación asociados a las invitaciones por correo electrónico no se aplicaban correctamente en el flujo de registro de nuevas cuentas. Un enlace de confirmación lleva al usuario al endpoint check_prereg_key_and_redirect, antes de ser redirigido a POST a /accounts/register/. El problema era que la comprobación ocurría en la parte check_prereg_key_and_redirect y no en /accounts/register/ - lo que significaba que uno podía enviar una clave de confirmación caducada y poder registrarse. El problema se ha corregido en Zulip versión 4.8. No se presentan soluciones conocidas y se aconseja a usuarios que actualicen lo antes posible

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-11-16 CVE Reserved
  • 2021-12-02 CVE Published
  • 2024-08-04 CVE Updated
  • 2025-03-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-613: Insufficient Session Expiration
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Zulip
Search vendor "Zulip"
Zulip
Search vendor "Zulip" for product "Zulip"
< 4.8
Search vendor "Zulip" for product "Zulip" and version " < 4.8"
-
Affected