Critical Security Update for fence-agents: Denial of Service Vulnerability in AlmaLinux 8
Summary
ALSA-2026:1906: Important: fence-agents security update. Affects fence-agents-aliyun versions < 4.2.1-129.el8_10.21. Fixed in 4.2.1-129.el8_10.21. How to fix ↓
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Background
The fence-agents package is a collection of scripts designed for remote power management of cluster devices. It plays a crucial role in ensuring the stability and reliability of cluster environments by allowing administrators to forcibly restart and remove failed or unreachable nodes. This functionality is essential for maintaining high availability in clustered systems, but it also presents potential security risks if not properly managed.
Vulnerability Detail
The vulnerability identified as CVE-2026-23490 is a Denial of Service (DoS) issue caused by memory exhaustion resulting from malformed RELATIVE-OID inputs processed by the pyasn1 library. This flaw can lead to significant service disruptions, as it may cause the affected services to become unresponsive or crash, thereby impacting the overall functionality of the cluster management system.
How To Fix
Minimum fixed version
4.2.1-129.el8_10.21
This is the first release that contains the fix.
sudo dnf update fence-agents-aliyunTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users may consider implementing input validation to filter out malformed RELATIVE-OID inputs until the patch can be applied. This can help mitigate the risk of triggering the vulnerability while maintaining service availability.
Conclusion
In summary, the fence-agents package has a critical vulnerability that can lead to Denial of Service attacks. Users are urged to update to the latest patched version to mitigate this risk. Implementing temporary workarounds can help maintain service availability until the update is applied.
See every vulnerability recorded for fence-agents-aliyun →
FAQ
CVE-2026-23490 is a Denial of Service vulnerability in the pyasn1 library used by fence-agents, which can lead to memory exhaustion and service disruptions.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Failure to address this vulnerability may result in service outages, impacting the stability and availability of your cluster management system.
It is recommended to regularly check for updates and apply security patches as soon as they are available to protect against vulnerabilities.
Vulert is a service that monitors and alerts in real-time for open-source vulnerabilities in your software using just a manifest file like package-lock.json.
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