CRLF injection in Python

Published: 2020-09-27 | Updated: 2020-11-23
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2020-26116
Exploitation vector Network
Public exploit N/A
Vulnerable software
Universal components / Libraries / Scripting languages


Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) CRLF injection

EUVDB-ID: #VU48592

Risk: Medium

CVSSv3.1: 6.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-26116

CWE-ID: CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')

Exploit availability: No


The vulnerability allows a remote attacker to inject arbitrary data in server response.

The vulnerability exists due to insufficient validation of attacker-supplied data in "http.client". A remote attacker can pass specially crafted data to the application containing CR-LF characters and modify application behavior.


Install updates from vendor's website.

Vulnerable software versions

Python: 3.0 - 3.8.4 rc1

External links

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.