In the Linux kernel, the following vulnerability has been resolved: use-after-free in tcp_write_timer_handler(). This vulnerability allows an attacker to potentially exploit kernel TCP sockets, leading to unpredictable behavior or crashes. The issue was identified via syzbot's repro, showcasing the kernel's TCP socket handling flaw.
The severity level of this vulnerability is currently classified as unknown. However, it is crucial for organizations using the Linux kernel to recognize that unresolved vulnerabilities can pose potential risks. For this specific CVE, the exploitation status is deferred, indicating that it is not actively being exploited in the wild.
Risk to organizations includes possible denial of service or instability in applications relying on kernel TCP sockets. Although the immediate urgency for addressing this vulnerability is low, organizations should remain aware of its existence and be prepared to implement patches when they become available.
Organizations should monitor for updates from the Linux kernel team regarding patches and updates related to this vulnerability.
Vulnerability Details
The vulnerability identified as CVE-2023-53781 pertains to a use-after-free condition in the tcp_write_timer_handler function within the Linux kernel. The issue arises when a kernel socket created during the SMC process is not properly released, leading to a potential use-after-free scenario.
With a CVSS score currently unscored, the risk associated with this vulnerability remains uncertain. It affects the Linux kernel, specifically the TCP socket handling, and was published on December 9, 2025.
Technical Analysis
The root cause of this vulnerability lies in the improper handling of kernel sockets during the release process. Specifically, when a socket is supposed to be freed, the state of the socket may not be TCP_CLOSE, resulting in TCP timers that can be fired later than intended.
The attack vector primarily involves local conditions where an attacker may exploit the kernel's handling of TCP sockets. The attack complexity is considered low, as it requires specific conditions to be met that could be easily manipulated by an attacker with local access.
No user interaction is required for an attack to succeed, making this vulnerability particularly concerning. The vulnerability impacts confidentiality, integrity, and availability, with the potential for denial of service or other impacts depending on the exploitation.
Risk & Impact Analysis
Real-world deployment risk associated with CVE-2023-53781 is moderate due to the use-after-free issue that could lead to kernel crashes or instability. The blast radius for organizations utilizing the Linux kernel is significant, as many systems rely on it for core functionalities.
The urgency for organizations to address this vulnerability is currently classified as low due to the deferred status of the CVE. However, organizations are encouraged to keep abreast of updates and patches as they may represent a significant risk if left unaddressed.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of the Linux kernel prior to the patch addressing CVE-2023-53781 are potentially affected. Organizations are advised to apply the relevant updates as they become available.
Mitigation & Remediation
Organizations should monitor for patches and updates from the Linux kernel team and apply them as soon as they are released. In the absence of a patch, organizations may consider temporary workarounds, such as restricting access to affected systems or employing monitoring solutions until a fix is available.
For more comprehensive security measures, organizations can enhance their security posture through penetration testing and regular system audits.
Detection Guidance
Organizations should monitor logs for indicators of exploitation attempts related to this vulnerability. Look for unusual TCP socket behavior and the firing of TCP timers, which may indicate attempts to abuse the use-after-free condition.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2023-53781 lies in its representation of the challenges in managing kernel memory. This vulnerability emphasizes the importance of rigorous testing and validation in kernel development processes.
As organizations continue to deploy Linux systems, understanding such vulnerabilities becomes imperative for maintaining a secure environment. Security teams should incorporate lessons learned from this CVE into their development and operational practices.
For additional resources on securing Linux environments, organizations can refer to the following articles on application security best practices: Linux security best practices and secure coding practices.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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