CVE-2020-15694

Name: CVE-2020-15694
Creator: NVD / NIST
Published: 2020-08-14T19:15:12.677+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.33%

Last modified Jun 17, 2026

CVE-2020-15694 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. In Nim 1.2.4, the standard library httpClient fails to properly validate the server response. For example, httpClient.get().contentLength() does not raise any error if a malicious server provides a negative Content-Length.. EPSS estimates a 2.33% chance of exploitation in the next 30 days.

Description

In Nim 1.2.4, the standard library httpClient fails to properly validate the server response. For example, httpClient.get().contentLength() does not raise any error if a malicious server provides a negative Content-Length.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

2.33%

81.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

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#L241Patch, 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#L241Patch, 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-2020-15694?

How severe is CVE-2020-15694?

CVE-2020-15694 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.33% probability of exploitation in the next 30 days.

How do I fix CVE-2020-15694?

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-2020-15694?

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

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Source: NVD / NIST