Ubuntu alert USN-8198-1 (python-tornado)

From:
             
 
noreply+usn-bot@canonical.com
To:
             
 
ubuntu-security-announce@lists.ubuntu.com
Subject:
             
 
[USN-8198-1] Tornado vulnerabilities
Date:
             
 
Thu, 23 Apr 2026 12:01:46 +0000
Message-ID:
             
 
<E1wFskc-0005wt-Jn@lists.ubuntu.com>
==========================================================================
Ubuntu Security Notice USN-8198-1
April 22, 2026

python-tornado vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in Tornado.

Software Description:
- python-tornado: scalable, non-blocking web server and tools

Details:

It was discovered that Tornado incorrectly handled parsing of large
multipart request bodies. An attacker could possibly use this issue to
cause a denial of service. (CVE-2026-31958)

It was discovered that Tornado did not properly validate characters in
cookie values. An attacker could possibly use this issue to inject
arbitrary cookie attributes. (CVE-2026-35536)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 25.10
  python3-tornado                 6.4.2-3ubuntu0.3

Ubuntu 24.04 LTS
  python3-tornado                 6.4.0-1ubuntu0.5

Ubuntu 22.04 LTS
  python3-tornado                 6.1.0-3ubuntu0.1~esm5
                                  Available with Ubuntu Pro

Ubuntu 20.04 LTS
  python3-tornado                 6.0.3+really5.1.1-3ubuntu0.1~esm5
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  python-tornado                  4.5.3-1ubuntu0.2+esm3
                                  Available with Ubuntu Pro
  python3-tornado                 4.5.3-1ubuntu0.2+esm3
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  python-tornado                  4.2.1-1ubuntu3.1+esm3
                                  Available with Ubuntu Pro
  python3-tornado                 4.2.1-1ubuntu3.1+esm3
                                  Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-8198-1
  CVE-2026-31958, CVE-2026-35536

Package Information:
  https://launchpad.net/ubuntu/+source/python-tornado/6.4.2...
  https://launchpad.net/ubuntu/+source/python-tornado/6.4.0...


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