In the Linux kernel, a vulnerability has been resolved that affects the virtuser device created via configfs. This vulnerability allows for improper handling of lookup tables, which can lead to significant issues during probe attempts. Specifically, when a probe fails due to an incorrect lookup table, the table is not removed. This behavior prevents subsequent probe attempts from succeeding, even if the original issue is corrected, unless the device is explicitly released. Additionally, cleanup is also necessary in the less likely event of a failure during platform_device_register_full().
Furthermore, a consistent memory leak in lookup_table->dev_id has been identified using kmemleak. This leak occurs when the live state is toggled between 0 and 1 with a correct lookup table. To address these issues, the function gpio_virtuser_remove_lookup_table() has been introduced as a counterpart to the existing gpio_virtuser_make_lookup_table(). This function is called from all necessary points to ensure proper cleanup and memory management.
The CVSS score for this vulnerability is 5.5, classified as medium severity, which highlights its potential impact on system availability. Organizations running affected versions of the Linux kernel should prioritize patching to mitigate the risks associated with this vulnerability.
The urgency for defenders is high due to the availability impact of this vulnerability, which can lead to system instability or crashes. Organizations should be vigilant in monitoring their systems for indications of this vulnerability being exploited.
Risk to organizations includes potential service disruptions, particularly for systems relying on the Linux kernel for critical operations. Immediate action for patching is strongly recommended.
Vulnerability Details
The vulnerability described is primarily associated with the Linux kernel, specifically affecting the virtuser device configuration via configfs. The vulnerability is documented under CWE-401, which refers to improper handling of resources leading to memory leaks.
The CVSS version is 3.1, with a vector string of CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating a local attack vector, low attack complexity, and low privileges required with no user interaction necessary.
The vulnerability has been marked as 'Modified' and has been published on 2025-01-21. The affected versions are all versions of the Linux kernel from 6.11 up to, but not including, 6.12.10, along with specific release candidates for version 6.13.
Technical Analysis
The root cause of this vulnerability stems from the failure to properly clean up lookup tables when a probe fails during device creation. Without proper cleanup, the system can experience a memory leak, leading to high availability impacts over time.
The attack vector is local, meaning an attacker needs access to the system to exploit this vulnerability. The attack complexity is low, as it does not require advanced skills or extensive knowledge of the system. Only low privileges are needed, and no user interaction is necessary for exploitation.
The impacts of this vulnerability are significant in terms of availability; systems may become unstable or crash due to the memory leak associated with the lookup tables. The integrity and confidentiality of the system remain unaffected.
Risk & Impact Analysis
The real-world deployment risk associated with this vulnerability is moderate. Systems relying heavily on the Linux kernel for critical operations could face service interruptions, leading to potential financial losses and reduced trust from clients.
Given the medium CVSS score, organizations need to take this vulnerability seriously. The impact radius is significant, especially for environments where uptime is critical, such as data centers and production servers.
Organizations should evaluate their systems and prioritize addressing this vulnerability in their patch cycles, particularly if they are running the affected Linux kernel versions.
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 6.11 up to, but not including, 6.12.10. Specific release candidates of version 6.13 are also affected.
Mitigation & Remediation
Organizations should apply patches to the Linux kernel at their earliest convenience. The recommended action is to upgrade to a version that is not affected by this vulnerability. If an immediate upgrade is not possible, organizations should consider implementing workarounds, such as reviewing device configurations to ensure proper cleanup of lookup tables.
Monitoring should be established to detect any anomalies in system behavior that may suggest exploitation of this vulnerability. Regular security assessments and penetration testing can help identify potential weaknesses before they are exploited.
For organizations looking to validate remediation efforts, conducting a penetration testing can be beneficial to ensure the patched systems are secure.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor system logs for indicators of abnormal behavior. Specific behavioral anomalies may include unexpected memory usage patterns or service interruptions.
Network signatures indicating manipulation of virtuser devices should also be established to alert security teams to possible intrusions.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-21661 lies in its illustration of the ongoing challenges faced in resource management within the Linux kernel. As systems become increasingly complex, vulnerabilities of this nature may become more common.
This vulnerability serves as a reminder for security teams to prioritize proper resource management and cleanup in their development processes. It also highlights the importance of regular security reviews in maintaining the integrity of critical systems.
Organizations are encouraged to review their vulnerability management programs to ensure all vulnerabilities are tracked and remediated in a timely manner.
For further insights on this and similar vulnerabilities, organizations should consider following relevant industry trends and updates through credible sources, such as vulnerability exposure severity trends and adapting their security strategies accordingly.
Lastly, organizations should remain vigilant about ongoing developments in the Linux kernel that may influence the security landscape for their systems.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)