In the Linux kernel, a vulnerability has been identified and resolved regarding the 'sctp: sysctl: plpmtud_probe_interval'. This issue arises from the improper use of 'current->nsproxy', which can lead to null pointer dereference errors, particularly when the current task is exiting. The vulnerability's severity is classified as medium, with a CVSS score of 5.5, indicating potential risks to system availability.
Risk to organizations includes potential service disruptions due to the high impact on availability. Although the vulnerability does not affect confidentiality or integrity, the availability impact could lead to significant operational challenges. Organizations using vulnerable versions of the Linux kernel should prioritize patching immediately.
As of now, there are no known exploits in the wild for this vulnerability, but it is crucial for defenders to remain vigilant and apply patches as they become available.
Organizations should assess their systems and schedule remediation to ensure they are not affected by this vulnerability.
Vulnerability Details
The Linux kernel vulnerability CVE-2025-21636 is characterized by an improper implementation related to the 'sctp' protocol. The CVSS vector for this vulnerability is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating a local attack vector with low complexity and low privileges required. The kernel version ranges affected include versions starting from 5.14 to less than 5.15.177, 5.16 to less than 6.1.125, 6.2 to less than 6.6.72, and 6.7 to less than 6.12.10.
The official description states that using the 'net' structure via 'current' can lead to inconsistencies and increase the risk of null pointer dereference errors. The vulnerability was disclosed on January 19, 2025, and is classified under CWE-476.
Technical Analysis
The root cause of this vulnerability stems from the improper handling of the 'net' structure in the Linux kernel. When accessing the 'net' structure via 'current', inconsistencies arise from fetching information from either the reader/writer's network namespace or only from the opener's namespace. Additionally, 'current->nsproxy' can be NULL under certain conditions, particularly when the current task is exiting.
The attack vector is local, meaning that an attacker must have access to the system to exploit this vulnerability. The attack complexity is low, and only low privileges are required for exploitation. No user interaction is necessary, which increases the risk of exploitation in environments where untrusted users have local access.
The impact on availability is classified as high, indicating that successful exploitation can lead to significant disruptions in kernel functionality. However, there are no impacts on confidentiality or integrity.
Risk & Impact Analysis
Organizations that utilize affected versions of the Linux kernel face increased risk of service outages due to this vulnerability. The potential for an attacker to exploit this vulnerability with local access poses a significant threat, particularly in multi-user environments or shared systems.
The urgency for remediation is categorized as high, given the medium severity and the potential impact on availability. Organizations should prioritize patching this vulnerability as part of their incident response and vulnerability management strategies.
Failure to address this vulnerability could lead to a broader attack surface, with a potential blast radius that affects multiple services relying on the Linux kernel.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of the Linux kernel are vulnerable to CVE-2025-21636:
1. All versions from 5.14 to 5.15.177 2. All versions from 5.16 to 6.1.125 3. All versions from 6.2 to 6.6.72 4. All versions from 6.7 to 6.12.10 5. Release candidates 6.13: rc1 to rc6
Mitigation & Remediation
Organizations should apply the latest patches provided by the Linux community to remediate this vulnerability. Specific version updates addressing the issue should be prioritized.
If a patch is not immediately available, organizations can consider implementing configuration hardening measures and monitoring for abnormal behavior in their systems.
For continuous security improvement, organizations should consider engaging in penetration testing to identify potential weaknesses in their systems.
Detection Guidance
Monitoring for log indicators that may denote exploitation attempts is crucial. Organizations should look for behavioral anomalies in system performance, particularly during operations that involve network functions managed by the kernel.
Network signatures should be established to detect unusual patterns of traffic that may indicate attempts to exploit vulnerabilities in the kernel.
AppSecure Threat Intelligence Insight
CVE-2025-21636 exemplifies the ongoing challenges in maintaining kernel security amid evolving threats. As organizations increasingly rely on Linux-based systems, understanding vulnerabilities like this is essential for proactive defense measures.
Security teams should establish a vulnerability management program to ensure timely identification and remediation of vulnerabilities in their environments.
Furthermore, organizations should remain informed about trends in kernel vulnerabilities, such as those documented in the 2025 vulnerability exposure severity trends, which highlight the critical nature of prompt updates and patches.
In conclusion, addressing vulnerabilities like CVE-2025-21636 reinforces the importance of a robust security posture in an increasingly complex threat landscape.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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