In the Linux kernel, a vulnerability has been identified that can lead to a NULL pointer dereference due to a race condition between the DRM scheduler and the IRQ execution thread. This vulnerability, classified as CVE-2025-21688, has been assigned a CVSS score of 4.7, indicating medium severity. The implications of this vulnerability are significant, as it could potentially cause system crashes and affect overall stability.
This vulnerability allows attackers to exploit the race condition between the job pointer being set to NULL and the assignment of new jobs. If the IRQ execution thread sets the job pointer to NULL after a new job has already been assigned, it results in a NULL pointer dereference when the GPU emits an interrupt, triggering a crash.
Risk to organizations includes possible system downtime and instability, affecting critical operations. Organizations should prioritize patching immediately to prevent exploitation of this vulnerability.
As of now, there is no known public exploit for this vulnerability, but the nature of the issue suggests that it may be leveraged in targeted attacks if left unaddressed.
Vulnerability Details
The vulnerability involves a race condition in the Linux kernel's DRM subsystem, specifically related to the v3d driver. The issue was introduced in a recent commit that attempted to improve job completion handling but inadvertently created the race condition. The commit is detailed in the official kernel documentation.
The CVSS score indicates that the attack vector is local, requiring low privileges and no user interaction. The availability impact is rated high, while confidentiality and integrity impacts are rated as none.
Technical Analysis
The root cause of this vulnerability is the race condition that arises when the job pointer is set to NULL after a job's completion. This leads to the potential for a NULL pointer dereference when the GPU interrupts the system while a new job is being assigned.
The attack vector is local, meaning that an attacker must have local access to the system to exploit this vulnerability. The attack complexity is classified as high, given the precise timing required to exploit the race condition. Privileges required are low, allowing a user with minimal access to potentially trigger the vulnerability.
No user interaction is required, as the exploitation can occur purely through the execution of jobs by the GPU. The impact on availability is categorized as high due to the potential for system crashes, while there is no impact on confidentiality or integrity.
Risk & Impact Analysis
Organizations running vulnerable versions of the Linux kernel are at significant risk for system instability. The potential for a crash due to NULL pointer dereference can lead to downtime, affecting business continuity and user trust.
The urgency for remediation is underscored by the high availability impact score. Organizations should address this vulnerability in their patch management cycles to minimize operational risks.
In light of the current exploitation status and the lack of known public exploit, the time to act is now. Proactive measures are essential to mitigate potential risks associated with this vulnerability.
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:
• Linux Kernel 5.15.177 and earlier • Linux Kernel 6.1.127 and earlier • Linux Kernel 6.6.74 and earlier • Linux Kernel 6.12.11 and earlier • Linux Kernel 6.13 and earlier
Mitigation & Remediation
Organizations should prioritize patching affected systems with the latest kernel updates. The necessary patches have been made available, and organizations must ensure that they are applied without delay.
For detailed guidance on the patching process and kernel updates, organizations can refer to the following resource: penetration testing services.
Detection Guidance
Organizations should monitor logs for indications of abnormal kernel behavior, especially related to job handling and execution threads. Key indicators include CPU usage spikes and unexpected crashes.
AppSecure Threat Intelligence Insight
The vulnerability represented by CVE-2025-21688 highlights the importance of robust design in kernel-level components. As systems become increasingly complex, the potential for race conditions poses significant risks.
Security teams should prioritize regular vulnerability assessments and adopt comprehensive strategies to mitigate the risk of similar issues. Engaging in vulnerability management programs can significantly enhance overall security posture.
Additionally, leveraging penetration testing methodologies can help organizations identify weaknesses before they are exploited.
Finally, organizations should stay informed about evolving threats and ensure that they have effective incident response plans that include strategies for addressing kernel vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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