In the Linux kernel, a vulnerability has been identified related to the 'sctp: sysctl: cookie_hmac_alg' functionality. The issue arises from the use of the 'current->nsproxy' structure, which can lead to inconsistencies and potential null pointer dereferences. This vulnerability allows attackers to compromise system availability, making it critical for organizations utilizing affected Linux kernel versions to address it promptly.
The CVSS score for this vulnerability is 5.5, classifying it as medium severity. This score reflects the potential impacts on system availability, which are deemed high, while confidentiality and integrity impacts are assessed as none. Organizations should assess their exposure to this vulnerability, particularly those running on versions of the Linux kernel that fall within the specified ranges.
Risk to organizations includes potential disruptions in service due to system instability. The urgency for defenders is high due to the nature of the vulnerability and its potential exploitation. Organizations should prioritize patching immediately to mitigate risks associated with this vulnerability.
As of the latest updates, there are no known exploits or public proof-of-concept code associated with this vulnerability. However, attackers may leverage the weaknesses introduced by this flaw to impact system operations, emphasizing the need for swift remediation.
Vulnerability Details
The vulnerability in the Linux kernel involves the 'sctp: sysctl: cookie_hmac_alg' functionality, where using the 'current->nsproxy' structure is discouraged. This is due to the possibility of obtaining inconsistent information from the network namespaces, along with the risk of null pointer dereferencing when the current task is exiting. The official CVE description notes that the 'net' structure can be accessed from 'table->data' using the 'container_of()' method.
The CVSS score of 5.5 indicates a medium severity classification. The attack vector is local, requiring low complexity and low privileges, with no user interaction necessary. The impacts on confidentiality and integrity are none, while the availability impact is high.
Affected versions include various iterations of the Linux kernel, specifically versions ranging from 3.8 up to 6.1.125, as well as subsequent versions including 6.2 to 6.6.72, and 6.7 to 6.12.10. Additionally, specific release candidates from version 6.13 are also impacted.
Technical Analysis
The root cause of the vulnerability lies in the improper handling of the 'current->nsproxy' structure, which can lead to inconsistencies in network namespace information retrieval. The attack vector is local, necessitating low privileges and low complexity for exploitation, with no user interaction required. The impact on availability is categorized as high, meaning that successful exploitation could result in significant service disruption.
Risk & Impact Analysis
Organizations that utilize affected versions of the Linux kernel should be acutely aware of the real-world risks associated with this vulnerability. The potential for service disruption due to high availability impact means that any exploitation could lead to significant operational challenges, making it imperative for organizations to prioritize remediation.
Given the CVSS score of 5.5, organizations are advised to incorporate this vulnerability into their immediate remediation cycle. Understanding the blast radius of this vulnerability is crucial, as it could affect multiple systems if not addressed promptly.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects the Linux kernel across various versions. Specifically, the impacted versions include those from 3.8 up to 6.1.125, in addition to versions 6.2 to 6.6.72 and 6.7 to 6.12.10. Release candidates of version 6.13 are also vulnerable.
Mitigation & Remediation
Organizations should apply the patches released to mitigate this vulnerability effectively. It is essential to review the specific updates available for the Linux kernel versions in use. For those unable to immediately apply patches, consider implementing workarounds such as isolating affected services or adjusting configurations to limit exposure.
Additionally, organizations may benefit from engaging in penetration testing to validate the effectiveness of their remediation efforts.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor logs for unusual access patterns and errors related to the 'sctp: sysctl: cookie_hmac_alg' functionality. Behavioral anomalies such as unexpected service disruptions or crashes should also be investigated. Network signatures may assist in identifying potential attempts to exploit this flaw.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-21640 underscores the necessity for continuous monitoring and updating of the Linux kernel. This vulnerability represents a trend of increasing complexity in kernel-level operations and the potential for local exploitation that could lead to significant system impacts.
Security teams should prioritize establishing robust vulnerability management programs to identify and address similar risks proactively. Engaging in regular vulnerability management practices is crucial to maintaining security resilience.
As the landscape of vulnerabilities evolves, organizations must stay informed about emerging threats and adapt their security strategies accordingly. This includes investing in penetration testing methodologies that can help assess their defenses against similar issues.
Ultimately, organizations should adopt a proactive approach to security, understanding that vulnerabilities like CVE-2025-21640 are part of a broader threat landscape requiring ongoing vigilance.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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