In the Linux kernel, a vulnerability has been identified and resolved. This vulnerability is characterized by a null pointer dereference, which could lead to system interruption. The vulnerability was categorized as having a CVSS score of 5.5, classifying it as medium severity. Given the potential impact on system availability, organizations should prioritize patching to mitigate risks associated with this vulnerability.
The vulnerability arises from a reverted commit that attempted to fix an issue related to freeing virtual ttys. The original commit did not adequately address the problem and instead introduced a null pointer dereference. Organizations using affected Linux kernel versions should take immediate action to apply the necessary patches.
Risk to organizations includes potential downtime or service disruption if the vulnerability is exploited. The urgency for defenders is high, as the availability of systems is critical for operational continuity. Immediate attention to remediation is warranted to prevent operational impacts.
This vulnerability is not known to be actively exploited, but its effects on availability necessitate prompt patching. Organizations should monitor their systems and ensure they are running the latest kernel versions to mitigate this risk.
Vulnerability Details
The vulnerability, identified as CVE-2023-52564, is present in certain versions of the Linux kernel. The official description notes that the vulnerability stems from a null pointer dereference introduced by a reverted commit meant to fix a use-after-free (UAF) condition in the function gsm_cleanup_mux(). The CVSS score for this vulnerability is 5.5, indicating a medium severity level.
The attack vector is local, requiring low privileges and no user interaction. The impact on availability is categorized as high, while confidentiality and integrity impacts are noted as none. The vulnerability affects the Linux kernel, particularly versions between 5.10.190 to 5.10.198, 5.15.124 to 5.15.134, and 6.1.43 to 6.1.56, as well as newer release candidates.
Technical Analysis
The root cause of the vulnerability lies in the improper handling of the reference counter for the DLCI (Data Link Connection Identifier). In the function gsm_cleanup_mux(), the code attempts to free virtual ttys by calling gsm_dlci_release() for each active DLCI. The dlci_put() function is designed to decrement the reference counter, which ultimately leads to calling gsm_dlci_free(). This function clears the pointer that is subsequently checked in gsm_cleanup_mux(). Thus, clearing the pointer again in gsm_cleanup_mux() becomes unnecessary and introduces a null pointer dereference.
The attack vector for this vulnerability is local, meaning an attacker must have access to the system to exploit the flaw. The complexity of the attack is low, and the privileges required are also low, making exploitation feasible for low-privileged users. There is no requirement for user interaction, which further increases the risk. The null pointer dereference can lead to high availability impact, potentially causing system crashes or instability.
Risk & Impact Analysis
Real-world deployment risks associated with this vulnerability include potential system crashes and service disruptions, which can impact business operations. The blast radius could extend to any service relying on the affected Linux kernel versions, making it critical for organizations to understand the potential damage. Given the medium severity and the high availability impact, organizations should address this vulnerability in their priority patch cycle.
With the CVSS score of 5.5, this vulnerability poses a moderate risk to organizations. Even though it is not currently known to be actively exploited, the lack of safeguards around the dlci_put() function increases its risk profile. Organizations are strongly encouraged to patch their systems immediately to prevent possible exploitation.
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:
• Versions 5.10.190 to 5.10.198
• Versions 5.15.124 to 5.15.134
• Versions 6.1.43 to 6.1.56
• Versions 6.5 to 6.5.6
• Release candidates 6.6: rc1, rc2, rc3
Mitigation & Remediation
To mitigate the risks associated with this vulnerability, organizations should apply the latest patches provided by the Linux kernel maintainers. The patch information can be found at patch management services. Additionally, organizations should consider implementing strict access controls and monitoring for any unusual system behavior that could indicate exploitation attempts.
Detection Guidance
Organizations should monitor their systems for the following indicators:
• Log entries related to null pointer dereference errors.
• Unusual behavior patterns that suggest a potential exploitation of the vulnerability.
• Network traffic indicative of attempts to exploit the vulnerability.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2023-52564 highlights the importance of rigorous testing and validation of kernel changes. This vulnerability illustrates the potential pitfalls of code modifications that do not fully address underlying issues. Security teams should incorporate comprehensive testing practices in their development processes.
Understanding patterns in vulnerabilities can inform better coding practices and security measures. The trend of vulnerabilities arising from reverted patches indicates a need for careful review and testing of code before deployment.
Organizations are encouraged to maintain a proactive stance on security by regularly updating their systems and engaging in penetration testing to identify similar vulnerabilities before they can be exploited.
In conclusion, CVE-2023-52564 serves as a reminder of the importance of thorough validation processes in software development. Continuous learning from vulnerabilities will strengthen the security posture of organizations.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)