In the Linux kernel, a high-severity vulnerability has been identified that allows for a use-after-free condition during session logoff. Specifically, the vulnerability relates to the handling of the sess->user object, which can be accessed simultaneously by multiple threads. This situation arises when another connection sends a session setup request while the session is in the process of being freed, potentially leading to a denial of service or arbitrary code execution.
The CVSS score for this vulnerability is 7.8, indicating high severity. Organizations using any affected version of the Linux kernel should act swiftly to address this issue to prevent potential exploitation, especially given the high exploitability score associated with this vulnerability.
Risk to organizations includes the possibility of unauthorized access and system instability, making it critical for defenders to implement patches or mitigations as soon as they are available.
Organizations should prioritize patching immediately.
Vulnerability Details
The vulnerability is tracked as CVE-2025-37899 and pertains to a use-after-free issue in the ksmbd component of the Linux kernel. It was resolved in recent patches, and the vulnerability is classified under CWE-416.
Published on May 20, 2025, this vulnerability affects multiple versions of the Linux kernel, particularly those versions ranging from 5.15 up to, but not including, 6.12.28, as well as certain release candidate versions of 6.15.
The CVSS vector for this vulnerability is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating that it requires local access with low complexity, low privileges, and no user interaction. The impacts on confidentiality, integrity, and availability are all rated as high.
Technical Analysis
The root cause of this vulnerability lies in the improper management of session objects within the Linux kernel, particularly in the context of concurrent access by multiple threads. The attack vector is local, meaning that an attacker must have access to the system to exploit this vulnerability.
Given the low attack complexity and the requirement for low privileges, this vulnerability can be exploited by users with limited access, potentially leading to further compromise of the system.
User interaction is not required for exploitation, making this vulnerability particularly dangerous in environments where multiple users operate concurrently.
The impact on confidentiality, integrity, and availability is significant, as attackers may leverage this vulnerability to gain unauthorized access, manipulate data, or disrupt services.
Risk & Impact Analysis
Organizations using affected versions of the Linux kernel face significant risk, particularly those operating in multi-user environments. The potential for unauthorized access and system instability due to this vulnerability necessitates immediate action.
The blast radius for this vulnerability is wide, affecting any system using the vulnerable kernel versions. The urgency for remediation is underscored by the high CVSS score and the known availability of exploits, which increases the likelihood of cybercriminals targeting these vulnerabilities.
Organizations should address this vulnerability in their priority patch cycle to mitigate risks and protect their infrastructure.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of the Linux kernel are affected by this vulnerability:
All versions prior to vendor patch, specifically those ranging from 5.15 up to, but not including, 6.12.28, and certain release candidates of 6.15.
Mitigation & Remediation
Organizations should prioritize applying the latest patches provided by the Linux vendor to remediate this vulnerability. If patches are not immediately available, consider implementing workarounds such as restricting access to affected systems or monitoring for unusual activity.
For further assistance in validating the effectiveness of remediation efforts, organizations can utilize penetration testing services.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor for abnormal session behaviors, unusual access patterns, and log indicators associated with user sessions.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-37899 reflects ongoing challenges in managing concurrency in complex systems like the Linux kernel. Security teams should analyze this incident to refine their processes surrounding vulnerability management and incident response.
This vulnerability represents a critical learning opportunity for organizations managing multi-threaded applications. The insights gained can enhance defensive programming practices, ensuring that similar vulnerabilities are less likely to occur in the future.
For organizations seeking to bolster their security posture, the following resources can provide additional guidance: penetration testing methodology, vulnerability management programs, and continuous security testing best practices.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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