CVE-2019-6802: CRLF Injection in pypiserver
Summary
CVE-2019-6802: CRLF Injection in pypiserver 1.2.5 and below allows attackers to set arbitrary HTTP headers and possibly conduct XSS attacks via a %0d%0a in a URI. Affects pypiserver versions < 1.2.6. Fixed in 1.2.6. How to fix ↓
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Background
pypiserver is a PyPI-compatible server for serving Python packages. It allows users to host their own Python package index and easily distribute packages. This vulnerability affects pypiserver versions 1.2.5 and below. The vulnerability allows attackers to set arbitrary HTTP headers and potentially conduct XSS attacks by injecting %0d%0a (CRLF) characters in a URI.
Vulnerability Detail
The CRLF Injection vulnerability in pypiserver allows attackers to manipulate HTTP headers and potentially execute cross-site scripting (XSS) attacks. By injecting %0d%0a characters in a URI, attackers can set arbitrary headers, leading to various security risks. This vulnerability can be exploited to perform session hijacking, cache poisoning, and other malicious activities.
How To Fix
Latest published version: 2.4.2 as of 23 Oct 2026
pip install --upgrade "pypiserver==2.4.2"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
1.2.6
This is the first release that contains the fix.
pip install --upgrade "pypiserver==1.2.6"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
There is no known workaround for this vulnerability. It is recommended to upgrade to the latest version of pypiserver to mitigate the risk.
Conclusion
The CRLF Injection vulnerability in pypiserver can be exploited to manipulate HTTP headers and potentially conduct XSS attacks. It is crucial to upgrade to pypiserver version 1.2.6 or later to mitigate the risk. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for pypiserver →
FAQ
pypiserver is a PyPI-compatible server for hosting Python packages.
Versions 1.2.5 and below of pypiserver are affected by this vulnerability.
This vulnerability allows attackers to manipulate HTTP headers and potentially conduct XSS attacks, leading to various security risks.
To fix this vulnerability, upgrade to pypiserver version 1.2.6 or later.
There is no known workaround for this vulnerability. It is recommended to upgrade to the latest version of pypiserver.
References
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