Critical Memory Leak Vulnerability in Linux Kernel's vmxnet3 Driver
Summary
CVE-2025-37799: In the Linux kernel, the following vulnerability has been resolved: vmxnet3: Fix malformed packet sizing in vmxnet3_process_xdp vmxnet3 driver's XDP handling is buggy for packet sizes using ring0 (that is, packet sizes b... Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing essential services for hardware and software interactions. The vmxnet3 driver is a virtual network interface card (NIC) driver designed for high-performance networking in virtualized environments. This driver is crucial for ensuring efficient data transmission and connectivity in systems utilizing VMware virtualization. However, a recent vulnerability has been identified that affects the handling of packet sizes in the vmxnet3 driver, potentially leading to memory leaks and data exposure.
Vulnerability Detail
The vulnerability, identified as CVE-2025-37799, arises from a flaw in the vmxnet3 driver's XDP (eXpress Data Path) handling. Specifically, the driver mishandles packet sizes between 128 and 3k bytes, leading to connectivity issues and the leakage of uninitialized kernel data onto the network. This can result in packets being larger than intended, causing them to be dropped by network interfaces when MTU (Maximum Transmission Unit) limits are exceeded. The root cause is a change in the code that incorrectly adjusts packet length parameters, which can expose sensitive data from previous packets, posing a significant security risk.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can lower the MTU on the XDP load balancer to a value such as 1480. This adjustment allows packets to be transmitted without exceeding the MTU limit, thereby preventing packet drops and mitigating the immediate impact of the vulnerability.
Conclusion
The CVE-2025-37799 vulnerability in the Linux kernel's vmxnet3 driver poses significant risks related to memory leaks and data exposure. Users are strongly advised to update their systems to the latest patched versions of the Linux kernel to ensure security and stability. Temporary workarounds, such as adjusting MTU settings, can help mitigate immediate risks while awaiting updates.
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FAQ
CVE-2025-37799 is a vulnerability in the Linux kernel's vmxnet3 driver that causes incorrect handling of packet sizes, leading to potential memory leaks and data exposure.
This vulnerability can lead to connectivity issues and the leakage of sensitive data over the network, especially in virtualized environments using the vmxnet3 driver.
If you are using the vmxnet3 driver, it is crucial to update your Linux kernel to the latest patched version to mitigate the vulnerability.
Yes, you can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. You can check if your application is affected by visiting the Vulert playground at Vulert Scanner.
MTU (Maximum Transmission Unit) defines the largest size of a packet that can be sent over a network. In this vulnerability, incorrect packet sizing can lead to packets exceeding the MTU limit, causing them to be dropped.
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