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[USN-8087-2] python-cryptography regression

Posted on 16 March 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8087-2
March 16, 2026

python-cryptography regression
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

USN-8087-1 introduced a regression in python-cryptography

Software Description:
- python-cryptography: Cryptography Python library

Details:

USN-8087-1 fixed a vulnerability in python-cryptography. The update caused
a regression when using ECC algorithms with certain software. This update
fixes the problem.

We apologize for the inconvenience.

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 25.10
python3-cryptography 43.0.0-1ubuntu1.2

Ubuntu 24.04 LTS
python3-cryptography 41.0.7-4ubuntu0.4

Ubuntu 22.04 LTS
python3-cryptography 3.4.8-1ubuntu2.4

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

References:
https://ubuntu.com/security/notices/USN-8087-2
https://ubuntu.com/security/notices/USN-8087-1
https://launchpad.net/bugs/2144373

Package Information:
https://launchpad.net/ubuntu/+source/python-cryptography/43.0.0-1ubuntu1.2
https://launchpad.net/ubuntu/+source/python-cryptography/41.0.7-4ubuntu0.4
https://launchpad.net/ubuntu/+source/python-cryptography/3.4.8-1ubuntu2.4

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