USN-8134-1: pyasn1 vulnerabilities

Publication date

30 March 2026

Overview

Several security issues were fixed in pyasn1.


Packages

  • pyasn1 - ASN.1 library for Python

Details

It was discovered that pyasn1 could exhaust system resources when
attempting to decode a malformed certificate. An attacker could
possibly use this to cause a denial of service. (CVE-2026-23490)

Kevin Tu discovered that pyasn1 could exhaust system resources via
uncontrolled recursion when attempting to decode malicously-crafted
certificates. An attacker could possibly use this to cause a denial of
service. (CVE-2026-30922)

It was discovered that pyasn1 could exhaust system resources when
attempting to decode a malformed certificate. An attacker could
possibly use this to cause a denial of service. (CVE-2026-23490)

Kevin Tu discovered that pyasn1 could exhaust system resources via
uncontrolled recursion when attempting to decode malicously-crafted
certificates. An attacker could possibly use this to cause a denial of
service. (CVE-2026-30922)

Update instructions

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
20.04 LTS focal pypy-pyasn1 –  0.4.2-3ubuntu0.20.04.1~esm1  
python-pyasn1 –  0.4.2-3ubuntu0.20.04.1~esm1  
python3-pyasn1 –  0.4.2-3ubuntu0.20.04.1~esm1  
18.04 LTS bionic pypy-pyasn1 –  0.4.2-3ubuntu0.18.04.1~esm1  
python-pyasn1 –  0.4.2-3ubuntu0.18.04.1~esm1  
python3-pyasn1 –  0.4.2-3ubuntu0.18.04.1~esm1  
16.04 LTS xenial pypy-pyasn1 –  0.1.9-1ubuntu0.1~esm1  
python-pyasn1 –  0.1.9-1ubuntu0.1~esm1  
python3-pyasn1 –  0.1.9-1ubuntu0.1~esm1  
14.04 LTS trusty python-pyasn1 –  0.1.7-1ubuntu2.1+esm1  
python3-pyasn1 –  0.1.7-1ubuntu2.1+esm1  

Reduce your security exposure

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