Vulnerability identifier: #VU45739

Vulnerability risk: Medium

CVSSv3.1: 5.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-15694

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
nim
Universal components / Libraries / Programming Languages & Components

Vendor: nim-lang.org

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of server responses in the standard library httpClient. A remote attacker can pass specially crafted input to the application and perform a denial of service (DoS) attack or force the application to perform unexpected actions as demonstrated by the  httpClient.get().contentLength() that does not raise any error if a malicious server provides a negative Content-Length.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

nim: 1.2.4

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External links
http://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/httpclient.nim#L241
http://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.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.