In the Linux kernel, a vulnerability has been identified related to the use of 'current->nsproxy' in the 'sctp: sysctl: udp_port' function. This issue is categorized as medium severity with a CVSS score of 5.5, indicating a potential local attack vector with low complexity and low privileges required. The primary risk is high availability impact, which can affect system performance and stability.
The vulnerability arises from inconsistencies when obtaining information from the network namespace. Specifically, 'current->nsproxy' can be NULL under certain conditions, leading to a null-pointer dereference. This is particularly concerning when the current task is exiting, as noted by syzbot in their testing.
Given the potential severity and the fact that this vulnerability has been acknowledged and documented in various patches, organizations should prioritize patching immediately to mitigate risks. The impact of exploitation could lead to significant disruptions in service availability.
As of now, there is no public exploit available, and the vulnerability is not listed in the Known Exploited Vulnerabilities (KEV) catalog. However, the possibility of exploitation remains a concern, given the nature of the vulnerability.
Organizations are advised to assess their systems and apply the necessary updates to ensure that they are safeguarded against this vulnerability.
Vulnerability Details
The vulnerability in question is documented as follows:
CVE ID: CVE-2025-21637
Description: In the Linux kernel, the vulnerability arises from the use of 'current->nsproxy' in the 'sctp: sysctl: udp_port' function, which can lead to null-pointer dereference errors.
Severity: Medium (CVSS score of 5.5)
Affected Products: Linux Kernel versions 5.11 through 5.15.177, 5.16 through 6.1.125, 6.2 through 6.6.72, and 6.7 through 6.12.10, as well as various release candidates of version 6.13.
CWE Classification: CWE-476
Technical Analysis
The root cause of this vulnerability is related to the reliance on the 'current' structure within the Linux kernel for network namespace operations. Specifically, using 'current->nsproxy' is discouraged due to potential null dereferencing. The attack vector for this vulnerability is local, meaning that an attacker would need local access to the machine to exploit it.
The attack complexity is classified as low, and it requires low privileges. In terms of user interaction, none is required for successful exploitation. The impact on confidentiality and integrity is minimal, but there is a high impact on availability, which poses a risk to operational continuity.
Risk & Impact Analysis
Risk to organizations includes potential service disruptions due to high availability impact. The nature of the vulnerability means that if exploited, the results could lead to significant downtime or instability within affected systems.
Given the medium severity of the CVSS score, organizations should address this vulnerability in their priority patch cycle. While it is not currently known to be actively exploited, the implications of an available exploit could pose severe risks.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects the following Linux Kernel versions:
• All versions from 5.11 to 5.15.177 • All versions from 5.16 to 6.1.125 • All versions from 6.2 to 6.6.72 • All versions from 6.7 to 6.12.10 • Release candidates of version 6.13 (rc1 to rc6)
Mitigation & Remediation
Organizations should prioritize patching immediately. The following actions are recommended:
• Apply the latest patches from the Linux kernel repository.
• Ensure that systems are updated to the latest stable version to mitigate potential risks.
• Consider implementing network controls to limit access to critical systems.
For further guidance, organizations can refer to the penetration testing services offered by AppSecure.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor for:
• Log indicators related to system crashes or unexpected behavior.
• Behavioral anomalies in network traffic that may indicate exploitation attempts.
AppSecure Threat Intelligence Insight
This vulnerability highlights the ongoing challenges within the Linux kernel and the importance of proactive security measures.
Security teams are encouraged to adopt a comprehensive vulnerability management program that integrates regular assessments and updates.
Additionally, understanding the implications of such vulnerabilities can inform better risk management strategies.
For more insights, consider reviewing our guide on penetration testing methodology to better prepare for potential threats.
Ultimately, addressing vulnerabilities like CVE-2025-21637 is critical to maintaining the integrity and availability of Linux-based systems.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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