In the Linux kernel, a high-severity vulnerability has been identified that could lead to a use-after-free (UAF) condition. This vulnerability allows for improper synchronization when freeing resources during CPU hot unplug, posing a significant risk to system integrity.
The CVSS score for this vulnerability is 7.8, indicating a high severity. The implications of this vulnerability are serious, as attackers may leverage it to exploit systems running affected versions of the Linux kernel. Organizations should prioritize patching immediately to mitigate potential risks.
This vulnerability was introduced in commit 1ec3b5fe6eec when the kernel started using the crypto_acomp API for hardware acceleration. The lack of proper preemption handling means that if a CPU is hot unplugged while its associated context is in use, it can lead to a UAF bug as resources are freed unexpectedly.
Organizations using vulnerable versions of the Linux kernel should schedule remediation as soon as possible to ensure system stability and security.
Vulnerability Details
The vulnerability, classified under CWE-416, affects the Linux Kernel versions from 5.11 up to but not including 6.12.12. The vulnerability allows attackers to exploit the system by triggering the use-after-free condition during ongoing operations on a different CPU, potentially leading to unauthorized access or system crashes.
The official CVE description details that the issue arises in the functions zswap_compress() and zswap_decompress(), where the per-CPU acomp_ctx is used without proper synchronization mechanisms.
To mitigate this vulnerability, it is recommended to ensure that the acomp_ctx.req is NULL before freeing resources and to control the synchronization of CPU hotplug callbacks.
Technical Analysis
The root cause of the vulnerability lies in the improper handling of CPU hotplug events, specifically related to the memory management within the Linux kernel. As the kernel uses the crypto_acomp API, which requires a sleepable context, preemption cannot be disabled. This means that operations can migrate to different CPUs, leading to potential UAF scenarios.
The attack vector for this vulnerability is local, with an attack complexity rated as low. An attacker with low privileges may exploit this vulnerability without requiring user interaction. The impacts of exploitation are severe, affecting confidentiality, integrity, and availability.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access to sensitive data and system instability. The potential blast radius is significant, as affected systems may become compromised if the vulnerability is exploited, affecting operational continuity.
Organizations should address this vulnerability in their priority patch cycle, especially those using the affected versions of the Linux kernel.
The urgency for remediation is high, given the real-world implications of a successful exploit. Security teams must implement the necessary patches as soon as they become available.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerable versions of the Linux kernel include all versions from 5.11 up to, but not including, 6.12.12, as well as specific release candidates of version 6.13.
Mitigation & Remediation
To remediate the vulnerability, organizations must apply the patches provided by the Linux kernel maintainers. It is essential to upgrade to the newest version of the Linux kernel that addresses this vulnerability.
If immediate patching is not feasible, organizations should consider implementing workarounds such as disabling CPU hotplugging or increasing monitoring for unusual behavior that might indicate exploitation attempts.
For more information on effective security practices, organizations can explore our penetration testing services to assess their security posture.
Detection Guidance
Organizations should monitor logs for indicators of unusual activity related to CPU hot unplug events. Behavioral anomalies that deviate from normal operational patterns should be closely examined.
Additionally, network signatures that correspond to the use of the vulnerable kernel features should be deployed to help in early detection of potential exploitation attempts.
AppSecure Threat Intelligence Insight
The long-term significance of this vulnerability lies in its demonstration of the complexities involved in resource management within the Linux kernel, particularly during CPU state transitions. Security teams must learn from this incident to strengthen their processes for handling state changes in critical components.
As organizations increasingly rely on dynamic resource management, the patterns observed in this vulnerability highlight the need for robust synchronization mechanisms during critical operational changes.
For insights into effective vulnerability management programs, organizations can refer to our vulnerability management program design guide.
Furthermore, to enhance security measures, organizations may consider adopting strategies outlined in our penetration testing methodology article.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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