Vulnerability Report

CVE-2021-43840

Title: Discourse Message Bus Path Traversal / LFI

Path Traversal / LFI

Proof Of Concept

No public PoC currently indexed for CVE-2021-43840.

CWE Category CWE-22
Published Date Dec 17, 2021
Modified Date Nov 21, 2024
Exploit Status Not Found
Score 4.4 CVSS v3.1
Exploit Probability (EPSS)
0.23%

Vulnerability Summary

CVE-2021-43840: 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.

Impacted Vendors

D
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Reference Links

https://github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb0447b4db2ba https://github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmm https://github.com/discourse/message_bus/commit/9b6deee01ed474c7e9b5ff65a06bb0447b4db2ba https://github.com/discourse/message_bus/security/advisories/GHSA-xmgj-5fh3-xjmm
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
4.4
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
6.5
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS v2.0
Source Entity [email protected]
Severity LOW
3.5
Access Vector
N/A
Authentication
N/A
RAW VECTOR AV:N/AC:M/Au:S/C:P/I:N/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2021-43840 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data or affected products updated.

PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N

Affected Stack

No specific products linked.