In the Linux kernel, a high-severity vulnerability identified as CVE-2025-21999 has been reported. This vulnerability allows for a use-after-free (UAF) condition in the function proc_get_inode(). It arises from a race condition between the removal of a module and the instantiation of inodes in the /proc filesystem. This flaw can lead to serious implications, including potential system crashes and unauthorized access.
The vulnerability has a CVSS score of 7.8, indicating a high severity level, which reflects the risk to organizations. Risk to organizations includes unauthorized access due to improper handling of module removal and inode management, which can potentially lead to exploitation by attackers.
Currently, there are no known exploits or public proof-of-concept (PoC) code available for this vulnerability. However, organizations should prioritize patching immediately to mitigate any potential risks associated with this vulnerability.
This vulnerability affects various versions of the Linux kernel, specifically those prior to the latest patches. Organizations running affected versions should take immediate action to ensure their systems remain secure.
Vulnerability Details
In the Linux kernel, the following vulnerability has been resolved: proc: fix UAF in proc_get_inode(). The problem arises from dereferencing pde->proc_ops after the /proc entry has been registered. The bug can occur unless a use_pde/unuse_pde() pair has been utilized. To avoid this, the necessary information for inode instantiation can be saved before the proc_register() in the PDE itself.
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 low attack complexity and low privileges with no user interaction needed. The impact can be high across confidentiality, integrity, and availability.
CWE classification for this vulnerability is CWE-416, which corresponds to 'Use After Free'.
Technical Analysis
The root cause of this vulnerability is a race condition between module removal and inode instantiation. The function proc_get_inode() may dereference a pointer to proc_ops after the associated module has been freed, leading to a potential use-after-free condition. This is particularly dangerous as it can corrupt the kernel's memory management, leading to crashes or arbitrary code execution.
The attack vector is local, meaning that an attacker must have local access to the system to exploit this vulnerability. The attack complexity is low, and it requires low privileges, which makes it feasible for attackers with limited access to exploit the system.
This vulnerability has significant implications for confidentiality, integrity, and availability, as it potentially allows attackers to manipulate kernel memory, leading to unauthorized access and system instability.
Risk & Impact Analysis
Organizations running affected versions of the Linux kernel face a considerable risk. If exploited, this vulnerability can allow attackers to gain unauthorized access to system resources, potentially leading to a complete compromise of the system. The urgency for organizations is high, given the widespread use of the affected kernel versions in various environments.
The impact of this vulnerability extends beyond individual systems, affecting the overall security posture of organizations. Attackers may leverage this vulnerability to execute arbitrary code, leading to data breaches, system outages, and significant financial losses.
As this vulnerability is classified as high severity, organizations should address it in their priority patch cycle. Given the potential for exploitation, a proactive approach to remediation is essential.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects the Linux kernel versions from 2.6.23 up to but excluding 6.1.132, and from version 6.2 up to but excluding 6.6.85. Additionally, it affects versions from 6.7 up to but excluding 6.12.21, and from 6.13 up to but excluding 6.13.9, including specific release candidates of version 6.14.
Mitigation & Remediation
Organizations should prioritize patching the Linux kernel to the latest version to mitigate this vulnerability. The specific versions to upgrade to include any patched versions following the identified vulnerable releases. If immediate patching is not possible, implementing configuration hardening and network controls can help reduce exposure until patches are available.
Organizations should also implement continuous security testing to ensure their systems are secure against similar vulnerabilities in the future.
Detection Guidance
Monitoring logs for any unusual kernel behavior can help detect potential exploitation attempts. Anomalies in system performance or accessibility to /proc entries should also be closely monitored.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-21999 highlights the importance of rigorous testing and validation processes within kernel development. This vulnerability serves as a reminder of the need for proactive measures in securing kernel operations, particularly in the context of module management.
Security teams should take this opportunity to review and strengthen their patch management processes to ensure timely updates, thereby reducing the attack surface.
For further guidance on vulnerability management and security testing, organizations can refer to resources on vulnerability management programs and effective penetration testing methodologies to enhance their security posture.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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