In the Linux kernel, a medium-severity vulnerability has been identified, specifically related to the handling of BIG TCP packets. This vulnerability allows for issues in hardware offload of IPv6 packets with extension headers, particularly affecting devices that advertise NETIF_F_IPV6_CSUM. With a CVSS score of 5.5, this vulnerability poses a significant risk to organizations relying on affected Linux kernel versions.
The vulnerability was published on January 15, 2025, and has been classified as modified due to ongoing developments in addressing its implications. Risk to organizations includes potential unavailability of network services that rely on effective processing of BIG TCP packets. Given the nature of this vulnerability, organizations should prioritize patching immediately.
Currently, there are no known exploits or public proofs of concept available, which suggests this vulnerability is not actively exploited. However, the threat of future exploitation remains, and organizations should remain vigilant and apply necessary updates as they become available.
To mitigate this risk, organizations should review their current Linux kernel versions and apply patches from the vendors promptly to prevent potential disruptions in service.
Vulnerability Details
The vulnerability involves the re-enabling of NETIF_F_IPV6_CSUM offload for BIG TCP packets in the Linux kernel. The original commit that disabled this feature led to warnings for BIG TCP packets, indicating a failure in handling IPv6 extension headers. The warning logs exemplify the specific code paths affected, emphasizing the need for careful management of network packet processing.
The vulnerability is classified under the Medium severity category with a CVSS score of 5.5, indicating a low attack complexity and low privilege requirements. The attack vector is local, meaning an attacker would need local access to exploit this vulnerability.
Technical Analysis
The root cause of this vulnerability lies in the mismanagement of BIG TCP packet handling, specifically with how the kernel interacts with hardware offloading features. The complexity of attacks is low, allowing potential attackers with limited privileges to exploit the flaw. User interaction is not required, making this vulnerability more dangerous in environments with significant network exposure.
The impact assessment reveals that while confidentiality and integrity are not affected, the availability impact is rated as high. This means that successful exploitation could lead to significant disruptions in network services.
Risk & Impact Analysis
Organizations using vulnerable versions of the Linux kernel face real-world risks, particularly those utilizing BIG TCP packets in their networking applications. The dependency on the proper functionality of these packets can lead to service outages if left unaddressed. The potential blast radius of an attack exploiting this vulnerability could encompass all systems relying on the affected kernel versions.
Given the CVSS score of 5.5 and the lack of known exploits, organizations should still treat this vulnerability with urgency in their patch cycles, especially as the risk of exploitation can evolve.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Affected versions include multiple ranges of the Linux kernel, specifically: - All versions from 4.19.323 to < 4.20 - All versions from 5.4.285 to < 5.5 - All versions from 5.10.229 to < 5.11 - All versions from 5.15.171 to < 5.16 - All versions from 6.1.116 to < 6.1.124 - All versions from 6.6.60 to < 6.6.70 - All versions from 6.11.7 to < 6.12 - All versions from 6.12.1 to < 6.12.9 - All versions from 6.12 - All versions from 6.12:rc6 - All versions from 6.12:rc7 - All versions from 6.13:rc1 - All versions from 6.13:rc2 - All versions from 6.13:rc3 - All versions from 6.13:rc4 - All versions from 6.13:rc5.
Mitigation & Remediation
Organizations should patch their systems by upgrading to the latest stable version of the Linux kernel that addresses this vulnerability. If immediate patching is not possible, consider implementing network controls to limit exposure to potentially vulnerable services. Monitoring for unusual network behavior related to BIG TCP packet processing can also be an effective interim measure.
Continuous penetration testing can help identify any weaknesses in your network configurations that could be exploited until a permanent fix is applied.
Detection Guidance
To detect potential exploitation attempts, organizations should monitor logs for unexpected messages associated with skb_warn_bad_offload and similar warnings. Attention should be given to network traffic involving BIG TCP packets, as well as system performance metrics that may indicate resource exhaustion or unavailability.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-21629 highlights the ongoing evolution of network protocols and how dependent systems must adapt to new standards. This case also emphasizes the importance of rigorous testing and validation in software development, particularly for systems that handle complex networking functions.
Security teams should leverage insights from this vulnerability to enhance their defensive strategies and ensure comprehensive testing protocols are established. Furthermore, ongoing education regarding emerging vulnerabilities and their implications is vital in maintaining a robust security posture.
Understanding penetration testing methodology will provide teams with the necessary framework to address vulnerabilities such as this effectively.
Developing a robust vulnerability management program will enhance an organization's ability to respond quickly to threats and maintain operational integrity.
Cloud penetration testing guides can also provide valuable insights into how cloud-based applications are affected by such vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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