==========================================================================
Ubuntu Security Notice USN-8087-3
April 28, 2026

python-cryptography vulnerability
==========================================================================

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

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

python-cryptography could be made to expose sensitive information over the
network.

Software Description:
- python-cryptography: Cryptography Python library

Details:

USN-8087-1 fixed a vulnerability in python-cryptography. This update
provides the corresponding update to Ubuntu 16.04 LTS, Ubuntu 18.04 LTS,
and Ubuntu 20.04 LTS.

Original advisory details:

 It was discovered that python-cryptography incorrectly handled subgroup
 validation for SECT curves. A remote attacker could use this issue to
 perform a subgroup attack and possibly recover the least significant bits
 of private keys.

Update instructions:

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

Ubuntu 20.04 LTS
  python-cryptography             2.8-3ubuntu0.3+esm2
                                  Available with Ubuntu Pro
  python3-cryptography            2.8-3ubuntu0.3+esm2
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  python-cryptography             2.1.4-1ubuntu1.4+esm3
                                  Available with Ubuntu Pro
  python3-cryptography            2.1.4-1ubuntu1.4+esm3
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  python-cryptography             1.2.3-1ubuntu0.3+esm3
                                  Available with Ubuntu Pro
  python3-cryptography            1.2.3-1ubuntu0.3+esm3
                                  Available with Ubuntu Pro

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

References:
  https://ubuntu.com/security/notices/USN-8087-3
  https://ubuntu.com/security/notices/USN-8087-2
  https://ubuntu.com/security/notices/USN-8087-1
  CVE-2026-26007