In the Linux kernel, a high-severity vulnerability has been identified and resolved. This vulnerability allows for out-of-bounds access when preempted due to the behavior of the Kyber scheduler. The function __blk_mq_sched_bio_merge() retrieves context for the current CPU and passes it to ->bio_merge(). However, the thread can be preempted between these two calls, leading to potential garbage reads if a mismatched context is returned. This issue can lead to serious system instability and should be addressed immediately.
The severity of this vulnerability is classified as high, with a CVSS score of 7.8. Risk to organizations includes potential unauthorized access to sensitive data, system crashes, or other unpredictable behaviors that could disrupt normal operations. Given the potential impact, organizations utilizing affected versions of the Linux kernel should prioritize remediation.
Currently, no known exploit exists publicly, and the vulnerability is not listed in the KEV catalog, indicating that it is not actively exploited in the wild. However, the potential for exploitation remains, and organizations should be vigilant.
Organizations should prioritize patching immediately to ensure systems are secure against this vulnerability.
Vulnerability Details
The vulnerability arises from the Kyber scheduler's handling of context in the Linux kernel. Specifically, the function responsible for merging bio requests can inadvertently access out-of-bounds memory if a context mismatch occurs. This vulnerability is categorized under CWE-129, which pertains to improper validation of array index, leading to potential data corruption or system instability.
The CVSS score of 7.8 indicates a high severity level, which is primarily due to the potential impacts on confidentiality, integrity, and availability of the system. The publication date for this vulnerability is February 28, 2024.
Technical Analysis
The root cause of this vulnerability is the mishandling of context during preemption scenarios within the Kyber scheduler. The attack vector is local, requiring access to the system where the kernel operates. The attack complexity is low, as the conditions required to trigger the vulnerability can be met easily by a local user with standard privileges.
Privileges required for exploitation are low, and user interaction is not needed, making this vulnerability particularly concerning. The impacts on confidentiality, integrity, and availability are all rated as high, indicating severe consequences if the vulnerability is exploited.
Risk & Impact Analysis
The real-world risk associated with this vulnerability is significant, especially for organizations relying on the Linux kernel for critical operations. The potential for data corruption or unauthorized access due to this vulnerability creates a large blast radius for affected environments.
Given its high severity, organizations should assess their exposure immediately, particularly those running versions of the Linux kernel identified as vulnerable. The urgency for addressing this vulnerability is classified as high, and it should be included in the priority patch cycle.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of the Linux kernel are affected by this vulnerability: All versions from 4.18 up to but not including 5.4.120, 5.5 up to but not including 5.10.38, 5.11 up to but not including 5.11.22, 5.12 up to but not including 5.12.5, and 5.13:rc1. Organizations should review their deployments to identify any instances of these vulnerable versions.
Mitigation & Remediation
Organizations should urgently apply patches to the affected Linux kernel versions to mitigate this vulnerability. The patches are available through the official Linux kernel repositories. If immediate patching is not feasible, organizations should consider implementing configuration hardening and network controls to limit the impact of potential exploitation.
For ongoing protection, organizations may also benefit from engaging in penetration testing to identify other potential weaknesses in their environments.
Detection Guidance
Organizations should monitor system logs for any abnormal behavior or error messages related to the kernel. Indicators of compromise may include unexpected system crashes, unauthorized access attempts, or unusual resource usage patterns. Monitoring network traffic for suspicious connections could also provide early detection of attempts to exploit this vulnerability.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of robust security practices within the Linux kernel environment. Organizations must stay informed about vulnerabilities affecting their systems and take proactive measures to protect their assets. Additionally, this incident emphasizes the need for a comprehensive vulnerability management program to systematically identify and address potential risks.
Security teams should take this opportunity to review their incident response plans and ensure they are equipped to handle similar vulnerabilities in the future. Incorporating lessons learned from this vulnerability will enhance overall resilience against emerging threats.
For further insights on securing Linux systems, organizations can explore resources on Linux security best practices and consider engaging in targeted penetration testing to uncover additional vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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