CVE-2019-1020001

Possible arbitrary path traversal and file access via yard server

Impact

A path traversal vulnerability was discovered in YARD <= 0.9.19 when using yard server to serve documentation. This bug would allow unsanitized HTTP requests to access arbitrary files on the machine of a yard server host under certain conditions.

Thanks to CuongMX from Viettel Cyber Security for discovering this vulnerability.

Patches

Please upgrade to YARD v0.9.20 immediately if you are relying on yard server to host documentation in any untrusted environments.

Workarounds

For users who cannot upgrade, it is possible to perform path sanitization of HTTP requests at your webserver level. WEBrick, for example, can perform such sanitization by default (which you can use via yard server -s webrick), as can certain rules in your webserver configuration.

YARD is a documentation generation tool for the Ruby programming language. It enables the user to generate consistent, usable documentation that can be exported to a number of formats very easily, and also supports extending for custom Ruby constructs such as custom class level definitions.

Security Fix(es):

yard before 0.9.20 allows path traversal.(CVE-2019-1020001)

yard before 0.9.20 allows path traversal.

It was discovered that YARD before 0.9.11 does not block relative paths with an initial ../ sequence, which allows attackers to conduct directory traversal attacks and read arbitrary files. This issue only affected Ubuntu 16.04 LTS. (CVE-2017-17042)

It was discovered that yard before 0.9.20 is affected by a path traversal vulnerability, allowing HTTP requests to access arbitrary files under certain conditions. This issue only affected Ubuntu 18.04 LTS. (CVE-2019-1020001)

Aviv Keller discovered that the "frames.html" file within the Yard Doc's generated documentation is vulnerable to Cross-Site Scripting (XSS) attacks due to inadequate sanitization of user input within the JavaScript segment of the "frames.erb" template file. (CVE-2024-27285)