#VU24895 HTTP response splitting in Kotlin Ktor - CVE-2019-19389

Vulnerability identifier: #VU24895

Vulnerability risk: Medium

CVSSv4.0: 2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2019-19389

CWE-ID: CWE-113

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Kotlin Ktor
Server applications / Frameworks for developing and running applications

Vendor: JetBrains s.r.o.

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. 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 and XSS.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Kotlin Ktor: 0.1.2 - 1.2.5

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External links
https://gist.github.com/JLLeitschuh/6792947ed57d589b08c1cc8b666c7737
https://github.com/ktorio/ktor/pull/1408
https://twitter.com/JLLeitschuh/status/1210256191110230017?s=20

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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. However, proof of concept for this vulnerability is available.