#VU25103 Path traversal in Rack CORS Middleware - CVE-2019-18978

Vulnerability identifier: #VU25103

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-18978

CWE-ID: CWE-22

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Rack CORS Middleware
Other software / Other software solutions

Vendor: Calvin Yu

Description

The vulnerability allows a remote attacker to perform directory traversal attacks.

The vulnerability exists due to resource matching does not ensure that pathnames are in a canonical format when processing directory traversal sequences. A remote attacker can send a specially crafted HTTP request and read arbitrary files on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Rack CORS Middleware: 0.1.0 - 1.0.3

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External links
https://github.com/cyu/rack-cors/commit/e4d4fc362a4315808927011cbe5afcfe5486f17d
https://github.com/cyu/rack-cors/compare/v1.0.3...v1.0.4
https://lists.debian.org/debian-lts-announce/2020/02/msg00004.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.