Critical Security Update for python-pyasn1: Denial of Service Vulnerability
Summary
ALSA-2026:59243: Important: python-pyasn1 security update. Affects python3-pyasn1 versions < 0.6.2-1.el10_2.1. Fixed in 0.6.2-1.el10_2.1. How to fix ↓
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Background
Python is a widely-used interpreted programming language known for its versatility and ease of use. The python-pyasn1 package is a pure-Python implementation of ASN.1 (Abstract Syntax Notation One) data structures, which are commonly used in network protocols and cryptographic applications. This package allows developers to work with ASN.1 data types, providing essential functionality for applications that rely on this standard. However, vulnerabilities in this package can lead to significant security risks, particularly in scenarios where untrusted input is processed.
Vulnerability Detail
The vulnerability identified as CVE-2026-59886 in the pyasn1 package allows for a Denial of Service (DoS) attack via crafted ASN.1 REAL values. An attacker can exploit this vulnerability by sending specially crafted data that the pyasn1 library fails to handle correctly, potentially causing the application to crash or become unresponsive. This issue arises from improper validation of input data, which can lead to resource exhaustion or infinite loops, severely impacting the availability of the affected application.
How To Fix
Minimum fixed version
0.6.2-1.el10_2.1
This is the first release that contains the fix.
sudo dnf update python3-pyasn1Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate updating is not feasible, consider implementing input validation to sanitize ASN.1 REAL values before processing them. This can help mitigate the risk of exploitation until the packages can be updated.
Conclusion
The python-pyasn1 package has a critical vulnerability that can lead to Denial of Service attacks. It is crucial to update to the latest patched versions to ensure the security and availability of applications that depend on this package. Additionally, implementing input validation can serve as a temporary measure until updates are applied.
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FAQ
CVE-2026-59886 is a security vulnerability in the python-pyasn1 package that allows for Denial of Service attacks through crafted ASN.1 REAL values.
You can check if your application is affected by using the Vulert playground at Vulert Scanner, which allows you to monitor and alert for open-source vulnerabilities without requiring any installation.
Exploitation of this vulnerability can lead to application crashes or unresponsiveness, impacting the availability of services that rely on the affected packages.
Yes, a patch is available. You should update to version 0.6.2-1.el10_2.1 or later for both python3-pyasn1 and python3-pyasn1-modules.
If you cannot update immediately, implement input validation to sanitize ASN.1 REAL values as a temporary workaround until you can apply the necessary updates.
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