In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double free of TCP_Server_Info::hostname. When shutting down the server in cifs_put_tcp_session(), the cifsd thread might be reconnecting to multiple DFS targets before it realizes it should exit the loop, so @server->hostname can't be freed as long as the cifsd thread isn't done. This can lead to serious issues, including high availability impacts.
The CVSS score for this vulnerability is 5.5, classified as medium severity. Organizations should address this vulnerability in their patch cycle to mitigate the risk of potential exploitation, which could result in availability issues.
Risk to organizations includes potential system downtime due to the availability impact of this vulnerability. As of now, there is no known public exploit or proof of concept, but the nature of the vulnerability could allow attackers to disrupt services.
Organizations should prioritize patching immediately. The vulnerability was published on January 31, 2025, and has since been marked as modified, indicating that updates are necessary for all affected versions.
Vulnerability Details
The vulnerability allows for a double-free situation in the Linux kernel's SMB client implementation. This issue arises when shutting down the server in the cifs_put_tcp_session() function. The cifsd thread may attempt to reconnect to multiple Distributed File System (DFS) targets before completing its shutdown process.
The official CVSS score is 5.5, classified as medium severity, with the following vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. This indicates that the attack vector is local, the complexity is low, and it requires low privileges with no user interaction.
The affected product is the Linux kernel, and the vulnerability has been assigned a CWE classification of CWE-415.
Technical Analysis
The root cause of this vulnerability stems from improper resource management during the shutdown process of the CIFS client. The cifsd thread may not exit its loop appropriately, leading to an attempt to free the hostname multiple times. This results in a double-free condition, which can cause undefined behavior and potential crashes.
The attack vector for this vulnerability is local, meaning that an attacker must have local access to the system to exploit it. The attack complexity is low, and it requires low privileges to execute the attack. Additionally, no user interaction is needed, making it easier for potential attackers.
In terms of impacts, the confidentiality and integrity impacts are rated as none, whereas the availability impact is high. An attacker exploiting this vulnerability could potentially disrupt services, leading to system downtime.
Risk & Impact Analysis
The real-world deployment risk associated with this vulnerability is medium, as it affects a core component of the Linux operating system. Organizations utilizing vulnerable versions of the Linux kernel should assess their exposure to this risk, particularly those using systems that rely on the CIFS protocol for file sharing.
The potential blast radius includes any system using the affected Linux kernel versions, which could encompass a wide range of enterprise environments. Organizations should consider the urgency of this vulnerability based on its CVSS score and the fact that it is not currently listed in the KEV catalog, indicating that active exploitation is not confirmed.
Organizations should address this vulnerability in their priority patch cycle, given its medium severity and potential availability impacts. Remediation should be scheduled promptly to prevent any possible disruptions in service.
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: versions 5.14.19 to less than 5.15, 5.15.3 to less than 6.6.74, and 6.7 to less than 6.12.11. Additionally, specific release candidates such as 6.13:rc1 through 6.13:rc7 are also vulnerable.
Mitigation & Remediation
Organizations should ensure they are running an updated version of the Linux kernel that addresses this vulnerability. Specific patches have been released for the affected versions, and organizations are encouraged to review their current kernel version and apply the necessary updates.
For more information on how to conduct security assessments, organizations can refer to the application security assessment services offered.
Detection Guidance
Organizations should monitor logs for any anomalies related to the CIFS protocol and ensure that they are tracking any changes that may signal attempts to exploit this vulnerability. Behavioral anomalies or unexpected thread behavior may indicate attempts to exploit the double-free condition.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of rigorous testing and patch management for core system components. Organizations should prioritize continuous monitoring and vulnerability assessments to stay ahead of potential threats.
For further information on penetration testing methodology, see our penetration testing methodology guide.
Additionally, organizations can benefit from learning about vulnerability management programs to enhance their security posture.
Finally, understanding the trends in vulnerability exposure can significantly bolster defense strategies, which is discussed in our article on vulnerability exposure severity trends.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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