Debian Security Advisory

DLA-2808-1 python3.5 -- LTS security update

Date Reported:
05 Nov 2021
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2021-3733, CVE-2021-3737.
More information:

There were a couple of vulnerabilites found in src:python3.5, the Python interpreter v3.5, and are as follows:

  • CVE-2021-3733

    The ReDoS-vulnerable regex has quadratic worst-case complexity and it allows cause a denial of service when identifying crafted invalid RFCs. This ReDoS issue is on the client side and needs remote attackers to control the HTTP server.

  • CVE-2021-3737

    HTTP client can get stuck infinitely reading len(line) < 64k lines after receiving a 100 Continue HTTP response. This could lead to the client being a bandwidth sink for anyone in control of a server.

For Debian 9 stretch, these problems have been fixed in version 3.5.3-1+deb9u5.

We recommend that you upgrade your python3.5 packages.

For the detailed security status of python3.5 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: