In the Linux kernel, a critical vulnerability (CVE-2025-21756) has been reported that allows for a use-after-free condition concerning socket binding. This high-severity issue, with a CVSS score of 7.8, poses a significant risk to organizations using affected versions of the Linux kernel. Attackers may leverage this vulnerability to gain unauthorized access or manipulate system resources.
The vulnerability allows for socket unbinding during a transport reassignment. This defect is rooted in the way the kernel handles socket references, leading to potential exploitation opportunities if not addressed promptly. Organizations should prioritize patching immediately to safeguard their systems from this vulnerability.
The exploitation status indicates that a public exploit is available, and the risk of exploitation is high. With the potential for serious repercussions in a deployed environment, organizations are urged to take this threat seriously and assess their exposure.
A thorough understanding of this vulnerability's implications is essential for mitigating risks effectively. Security teams should evaluate their current systems and apply necessary updates without delay.
Vulnerability Details
The CVE-2025-21756 vulnerability in the Linux kernel relates specifically to socket management. The issue arises during the binding process where the kernel fails to maintain proper references, leading to a use-after-free condition. This vulnerability has been allocated a CVSS 3.1 score of 7.8, indicating a high severity level.
The vulnerability affects the Linux kernel versions from 5.5 up to but excluding 6.12.16, as identified in the CPE list. The impact on confidentiality, integrity, and availability is rated as high, meaning exploitation could lead to significant security breaches.
Published on February 27, 2025, this vulnerability is classified under CWE-416, which addresses use-after-free issues, making it critical for organizations using vulnerable kernel versions to address this flaw promptly.
Technical Analysis
The root cause of CVE-2025-21756 is a flaw in the socket management functionality of the Linux kernel. When a socket is created, it may not be properly unbound during a transport reassignment, leading to a reference count mismatch. This situation can lead to attempts to access memory that has already been freed, which is characteristic of a use-after-free vulnerability.
The attack vector for this vulnerability is local, meaning that an attacker would need local access to the system to exploit the vulnerability. The complexity of the attack is considered low, as it requires basic interaction with the socket API.
In terms of required privileges, only low privileges are needed for an attacker to exploit this vulnerability. No user interaction is necessary, which raises the risk level significantly.
The impacts on confidentiality, integrity, and availability are all rated high, indicating that successful exploitation could allow an attacker to gain unauthorized access, modify data, or disrupt service.
Risk & Impact Analysis
The real-world risk associated with CVE-2025-21756 is substantial. Organizations running affected versions of the Linux kernel face a high likelihood of exploitation due to the local attack vector and the low complexity required for an attack. If exploited, the vulnerability could lead to unauthorized access and significant operational disruptions.
Given the widespread use of Linux in various environments, including servers and embedded systems, the potential blast radius is considerable. Organizations should assess their systems urgently to understand the impact and prioritize remediation efforts.
The urgency of addressing this vulnerability cannot be overstated. Organizations should address it in their priority patch cycle to mitigate risks effectively.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects the Linux kernel versions from 5.5 to 6.12.16, specifically those versions that have not been patched. If version information is missing, it is recommended to state: 'All versions prior to vendor patch'.
Mitigation & Remediation
Organizations should prioritize the application of available patches to remediate CVE-2025-21756. The latest updates from the Linux kernel should be deployed to mitigate the risks associated with this vulnerability. For systems where a patch is unavailable, alternative workarounds should be considered, including configuration hardening and network controls.
Monitoring network traffic for any signs of unusual behavior is also recommended as a defensive measure. For further insights, organizations can refer to our penetration testing services.
Detection Guidance
To detect potential exploitation of CVE-2025-21756, organizations should monitor system logs for indicators of unusual socket behavior, particularly related to binding and unbinding actions. Behavioral anomalies, such as unexpected socket closures or errors during socket operations, should also raise red flags.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-21756 highlights the importance of robust socket management in the Linux kernel. As vulnerabilities of this nature can frequently lead to severe consequences, security teams should implement rigorous testing and monitoring to identify similar issues proactively. The patterns observed in this vulnerability serve as a reminder of the need for continuous evaluation of security practices.
Organizations are encouraged to stay informed about such vulnerabilities and adopt a proactive stance towards security. For further reading on security best practices, consider our penetration testing methodology and the importance of comprehensive security assessments.
Lastly, organizations should look into the implications of this vulnerability through our vulnerability management program design, ensuring all potential risks are effectively managed.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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