CVE-2020-15693

Name: CVE-2020-15693
Creator: NVD / NIST
Published: 2020-08-14T19:15:12.507+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 2.05%

Last modified Jun 17, 2026

CVE-2020-15693 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. In Nim 1.2.4, the standard library httpClient is vulnerable to a CR-LF injection in the target URL. An injection is possible if the attacker controls any part of the URL provided in a call (such as httpClient.get or httpClient.post), the User-Agent header value, or custom HTTP header names or values.. EPSS estimates a 2.05% chance of exploitation in the next 30 days.

Description

In Nim 1.2.4, the standard library httpClient is vulnerable to a CR-LF injection in the target URL. An injection is possible if the attacker controls any part of the URL provided in a call (such as httpClient.get or httpClient.post), the User-Agent header value, or custom HTTP header names or values.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS Probability

2.05%

78.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-74

Affected Software

Vendor	Product	Versions
Nim-Lang	Nim	<= 1.2.6

References

http://www.openwall.com/lists/oss-security/2021/02/04/2Exploit, Mailing List, Third Party Advisory
https://consensys.net/diligence/vulnerabilities/nim-httpclient-header-crlf-injection/Exploit, Third Party Advisory
https://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/httpclient.nim#L1023Patch, Third Party Advisory
https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.htmlRelease Notes, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/02/04/2Exploit, Mailing List, Third Party Advisory
https://consensys.net/diligence/vulnerabilities/nim-httpclient-header-crlf-injection/Exploit, Third Party Advisory
https://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/httpclient.nim#L1023Patch, Third Party Advisory
https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.htmlRelease Notes, Third Party Advisory

Timeline

Published: Aug 14, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-15693?

How severe is CVE-2020-15693?

CVE-2020-15693 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 2.05% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15693?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-15693?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST