#VU25747 HTTP response splitting in Puma - CVE-2020-5247

Vulnerability identifier: #VU25747

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-5247

CWE-ID: CWE-113

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Puma
Server applications / Web servers

Vendor: Evan Phoenix

Description

The vulnerability allows a remote attacker to perform HTTP splitting attacks.

The vulnerability exists due to software does not corrector process CRLF character sequences in a response header. A remote attacker can send specially crafted request containing CRLF sequence and make the application to send a split HTTP response.

Successful exploitation of the vulnerability may allow an attacker perform cache poisoning attack.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Puma: 3.0.0 - 3.0.2, 3.1.0 - 3.12.3, 3.2.0, 3.3.0, 3.4.0, 3.5.0 - 3.5.2, 3.6.0 - 3.6.2, 3.7.0 - 3.7.1, 3.8.0 - 3.8.2, 3.9.0 - 3.9.1, 4.0.0 - 4.0.1, 4.1.0 - 4.1.1, 4.2.0 - 4.2.1, 4.3.0 - 4.3.2

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External links
https://github.com/puma/puma/security/advisories/GHSA-84j7-475p-hp8v
https://owasp.org/www-community/attacks/HTTP_Response_Splitting
https://www.ruby-lang.org/en/news/2019/10/01/http-response-splitting-in-webrick-cve-2019-16254

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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.