Path traversal when MessageBus::Diagnostics is enabled

TRUNG BÌNH 6.5CVE-2021-43840 · GHSA-xmgj-5fh3-xjmm · Công bố 17/12/2021 · cập nhật 17/06/2026

Tóm tắt nhanh

CVE-2021-43840 là lỗ hổng mức TRUNG BÌNH (CVSS 6.5) ảnh hưởng message_bus, message bus (discourse).
Xác suất bị khai thác trong 30 ngày tới (EPSS): 1.9%, cao hơn 80.2% các lỗ hổng khác.
Cách xử lý: cập nhật lên 3.3.7 hoặc mới hơn.

Gói / sản phẩm	Phiên bản bị ảnh hưởng	Phiên bản đã vá
message_bus RubyGems	`< 3.3.7`	`3.3.7`
message bus discourse	`< 3.3.7`	`3.3.7`

Mô tả

Impact

Users who deployed message bus with diagnostics features enabled (default off) were 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.

Patches

Patched in 3.3.7.

Workarounds

Disable MessageBus::Diagnostics in production like environments.

Mô tả của NVD

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.