In the Linux kernel, a vulnerability has been identified related to the 'sctp: sysctl: auth_enable' function. This vulnerability allows for potential denial of service due to a null pointer dereference when the current task is exiting, as reported by syzbot. The vulnerability affects multiple versions of the Linux kernel, highlighting an urgent need for organizations to prioritize patching to mitigate associated risks.
The vulnerability has a CVSS score of 5.5, which classifies it as medium severity. This indicates that while there is some complexity involved in exploiting it, the availability impact is high, which could lead to significant service disruptions. Organizations running vulnerable versions should be especially vigilant.
Although there are no known exploits in the wild at this time, the nature of the vulnerability suggests that attackers may leverage it in future attacks, particularly if not addressed promptly. Therefore, organizations should take immediate action to apply the necessary patches and updates.
Organizations should prioritize patching immediately to prevent potential service disruptions and maintain operational integrity.
Vulnerability Details
The official description of this vulnerability states: In the Linux kernel, the following vulnerability has been resolved: 'sctp: sysctl: auth_enable: avoid using current->nsproxy'. Using the 'net' structure via 'current' is not recommended for various reasons, including inconsistency and potential null pointer dereference.
The CVSS score of 5.5 indicates a medium severity level, with an attack vector classified as local, and low complexity, requiring low privileges and no user interaction. The availability impact is rated high, meaning successful exploitation could lead to significant disruptions.
Vulnerable products include various versions of the Linux kernel, specifically versions from 3.10.41 to 6.12.10, as well as specific release candidates of version 6.13.
Technical Analysis
The root cause of this vulnerability lies in the improper handling of network namespace references within the SCTP (Stream Control Transmission Protocol) implementation in the Linux kernel. Specifically, using the 'current' task's network namespace can lead to inconsistencies and potential null pointer dereferences when tasks exit.
The attack vector is local, meaning that an attacker must have access to the system to exploit this vulnerability. The attack complexity is low, and it requires low privileges, making it accessible to unprivileged users on the system.
No user interaction is required, which increases the risk of exploitation. The vulnerability impacts availability, as an attacker could potentially cause a denial of service by triggering a null pointer dereference.
Risk & Impact Analysis
The real-world risk associated with CVE-2025-21638 is significant, particularly for organizations relying on the Linux kernel for critical infrastructure. Successful exploitation could lead to service interruptions, affecting business operations and potentially causing reputational damage.
The blast radius for this vulnerability is considerable, as it affects multiple versions across various Linux distributions. The urgency for organizations to address this vulnerability is underscored by its medium severity classification and high availability impact. Organizations should assess their deployments and prioritize remediation efforts based on the CVSS score.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of the Linux kernel include:
• All versions from 3.10.41 to below 3.11 • All versions from 3.12.20 to below 3.13 • All versions from 3.14.5 to below 5.4.290 • All versions from 5.5 to below 5.10.234 • All versions from 5.11 to below 5.15.177 • All versions from 5.16 to below 6.1.125 • All versions from 6.2 to below 6.6.72 • All versions from 6.7 to below 6.12.10 • All release candidates of version 6.13
Mitigation & Remediation
To remediate this vulnerability, organizations should apply the official patches provided by the Linux kernel maintainers. Upgrading to the latest stable version of the Linux kernel is strongly recommended.
In case immediate patching is not feasible, organizations should consider implementing network controls to limit access to the affected systems and closely monitor logs for any anomalous behavior.
For more information on penetration testing and security assessments, organizations can refer to penetration testing methodology to ensure their systems are secure.
Detection Guidance
Organizations should monitor system logs for any indicators of exploitation, including unexpected crashes or unusual behavior of the SCTP subsystem. Additionally, network traffic should be analyzed for anomalies that may suggest an ongoing exploitation attempt.
Behavioral anomalies, such as unexpected service interruptions or system resource exhaustion, should also be investigated thoroughly.
AppSecure Threat Intelligence Insight
CVE-2025-21638 exemplifies the ongoing challenges in maintaining the security of the Linux kernel. The nature of this vulnerability highlights the importance of rigorous testing and validation processes within the Linux development community.
As organizations increasingly rely on Linux for critical infrastructure, understanding the implications of vulnerabilities like this one is crucial. It serves as a reminder for security teams to implement a robust vulnerability management program to address risks proactively.
Moreover, the trends surrounding this vulnerability reflect broader patterns in software security, underscoring the necessity for continuous security assessments and continuous penetration testing to identify and remediate vulnerabilities before they can be exploited.
The strategic takeaway for security teams is to remain vigilant and responsive to emerging vulnerabilities, ensuring that appropriate measures are in place to protect their systems.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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