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[USN-8087-3] python-cryptography vulnerability

Posted on 29 April 2026
Ubuntu Security

==========================================================================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

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