// For flags

CVE-2021-43840

Path traversal in message_bus

Severity Score

6.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

message_bus is a messaging bus for Ruby processes and web clients. In versions prior to 3.3.7 users who deployed message bus with diagnostics features enabled (default off) are vulnerable to a path traversal bug, which could lead to disclosure of secret information on a machine if an unintended user were to gain access to the diagnostic route. The impact is also greater if there is no proxy for your web application as the number of steps up the directories is not bounded. For deployments which uses a proxy, the impact varies. For example, If a request goes through a proxy like Nginx with `merge_slashes` enabled, the number of steps up the directories that can be read is limited to 3 levels. This issue has been patched in version 3.3.7. Users unable to upgrade should ensure that MessageBus::Diagnostics is disabled.

message_bus es un bus de mensajería para procesos Ruby y clientes web. En las versiones anteriores a 3.3.7, los usuarios que desplegaron el bus de mensajes con las características de diagnóstico habilitadas (por defecto deshabilitadas) son vulnerables a un bug de salto de ruta, que podría conllevar a una revelación de información secreta en una máquina si un usuario no intencionado accediera a la ruta de diagnóstico. El impacto también es mayor si no se presenta un proxy para su aplicación web, ya que el número de pasos por los directorios no está limitado. Para las implementaciones que usan un proxy, el impacto varía. Por ejemplo, si una petición pasa por un proxy como Nginx con "merge_slashes" habilitado, el número de pasos hacia arriba en los directorios que pueden ser leídos está limitado a 3 niveles. Este problema ha sido parcheado en la versión 3.3.7. Los usuarios que no puedan actualizarse deberán asegurarse de que MessageBus::Diagnostics está deshabilitado

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
Medium
Authentication
Single
Confidentiality
Partial
Integrity
None
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-11-16 CVE Reserved
  • 2021-12-17 CVE Published
  • 2023-07-10 EPSS Updated
  • 2024-08-04 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Discourse
Search vendor "Discourse"
 Message Bus
Search vendor "Discourse" for product "Message Bus"
 < 3.3.7
Search vendor "Discourse" for product "Message Bus" and version " < 3.3.7"
ruby
Affected