Debian Security Advisory

DLA-2686-1 python-urllib3 -- LTS security update

Date Reported:
28 Jun 2021
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2018-20060, CVE-2019-11236, CVE-2019-11324, CVE-2020-26137.
More information:

Several vulnerabilities were discovered in python-urllib3, a HTTP client for Python.

  • CVE-2018-20060

    Urllib3 does not remove the Authorization HTTP header when following a cross-origin redirect (i.e., a redirect that differs in host, port, or scheme). This can allow for credentials in the Authorization header to be exposed to unintended hosts or transmitted in cleartext.

  • CVE-2019-11236

    CRLF injection is possible if the attacker controls the request parameter.

  • CVE-2019-11324

    Urllib3 mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to use of the ssl_context, ca_certs, or ca_certs_dir argument.

  • CVE-2020-26137

    Urllib3 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of putrequest().

For Debian 9 stretch, these problems have been fixed in version 1.19.1-1+deb9u1.

We recommend that you upgrade your python-urllib3 packages.

For the detailed security status of python-urllib3 please refer to its security tracker page at:

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: