CVE-2025-21671 is a high-severity vulnerability in the Linux kernel that allows for potential unauthorized access due to a use-after-free issue. This vulnerability is particularly concerning as it may enable attackers to exploit the system if they can reset a failed and uninitialized device. With a CVSS score of 7.8, the risk to organizations includes unauthorized access to sensitive data and disruption of services.
Given the potential impact, organizations should prioritize patching immediately. The vulnerability was published on January 31, 2025, and has since been modified, indicating ongoing concerns regarding its exploitation status. No public exploit has been confirmed, but the implications for systems running affected versions of the Linux kernel remain significant.
The urgency for defenders is high, as the vulnerability can lead to a variety of attacks if left unaddressed. Organizations must ensure that they are running the latest patched versions of the Linux kernel to mitigate these risks.
The vulnerability affects specific versions of the Linux kernel, which have been detailed in the configurations section. Organizations should conduct an inventory of their systems to identify any running vulnerable versions.
In summary, the presence of CVE-2025-21671 underscores the importance of regular updates and patch management within the Linux environment. Organizations must remain vigilant and proactive in addressing vulnerabilities to safeguard their systems.
Vulnerability Details
In the Linux kernel, the following vulnerability has been resolved: zram: fix potential UAF of zram table. If zram_meta_alloc failed early, it frees allocated zram->table without setting it NULL, which may cause zram_meta_free to access the table if a user resets a failed and uninitialized device.
The vulnerability is classified under CWE-416, indicating a use-after-free condition. It has a CVSS v3.1 score of 7.8, reflecting a high severity due to its potential impacts on confidentiality, integrity, and availability.
The vulnerability affects the Linux kernel, specifically versions between 6.1.122 and 6.1.127, 6.6.68 and 6.6.74, and 6.12.7 and 6.12.11.
Technical Analysis
The root cause of CVE-2025-21671 lies in the handling of memory allocation in the zram module of the Linux kernel. When the allocation for zram_meta fails, the kernel does not nullify the pointer to the table, which can lead to subsequent access attempts to a freed memory area.
The attack vector is local, meaning that an attacker would need local access to the system to exploit this vulnerability. The attack complexity is low, as it does not require any special conditions or user interaction.
The privilege required is low, allowing users with standard access to potentially exploit this vulnerability. There is no user interaction required, making it easier for an attacker to carry out the exploit.
The impacts of a successful exploit could include high confidentiality, integrity, and availability impacts, potentially leading to unauthorized data access or system crashes.
Risk & Impact Analysis
Real-world deployment of this vulnerability presents a significant risk to organizations using affected versions of the Linux kernel. The potential for unauthorized access can lead to data breaches, loss of sensitive information, and disruptions in service.
Organizations must understand that the blast radius of this vulnerability can be extensive, especially in environments where the Linux kernel is used across multiple systems and applications.
Given the CVSS score of 7.8 and the absence of a known exploit, organizations should address this vulnerability in their priority patch cycle to mitigate risks effectively.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of the Linux kernel include:
- All versions from 6.1.122 to 6.1.126 - All versions from 6.6.68 to 6.6.73 - All versions from 6.12.7 to 6.12.10
Mitigation & Remediation
Organizations should upgrade to the latest version of the Linux kernel to mitigate this vulnerability. Specifically, they should update to versions beyond the vulnerable ranges listed above.
In addition, organizations may consider implementing security best practices such as limiting local access to systems running the Linux kernel and employing monitoring solutions to detect any unauthorized access attempts.
For more information on penetration testing and assessing the security of your systems, organizations can refer to our penetration testing services for tailored security assessments.
Detection Guidance
Organizations should monitor logs for any indicators of unauthorized access attempts, especially around the use of the zram module. Behavioral anomalies that deviate from normal operations should also be flagged for investigation.
Network signatures that may indicate exploitation attempts should be developed and tested to strengthen defenses against potential attacks.
AppSecure Threat Intelligence Insight
CVE-2025-21671 highlights the ongoing need for security teams to remain vigilant and proactive in vulnerability management. As new vulnerabilities are discovered, understanding their implications and implementing timely remediation strategies is critical.
This vulnerability also reflects the necessity for continuous monitoring and assessment to identify and address emerging threats within the Linux ecosystem.
For further reading on security practices and methodologies, organizations can explore our penetration testing methodology to enhance their security posture.
Moreover, understanding the trends in vulnerabilities is essential. Our article on vulnerability management programs provides insights into effective strategies for managing and mitigating risks.
Known Exploitation Timeline
This vulnerability is not currently listed in the KEV catalog, indicating that there are no known exploitation cases at this time.
EPSS Risk Context
The EPSS score for CVE-2025-21671 is 0.00021, placing it in a low-risk percentile. This indicates that while the vulnerability is serious, the likelihood of exploitation remains low.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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