Out-of-Bounds Access in Linux Kernel's pktgen - CVE-2025-21680
Summary
CVE-2025-21680: In the Linux kernel, the following vulnerability has been resolved: pktgen: Avoid out-of-bounds access in get_imix_entries Passing a sufficient amount of imix entries leads to invalid access to the pkt_dev->imix_entries... Affects linux versions < 6.1.128-1. Fixed in 6.1.128-1. How to fix ↓
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Background
The Linux kernel is a core component of many operating systems, providing the essential interface between hardware and software. It manages system resources, hardware communication, and process management. The pktgen module is used for packet generation, allowing users to test network performance. However, it is susceptible to vulnerabilities that can lead to security risks, such as out-of-bounds access, which can compromise system integrity.
Vulnerability Detail
CVE-2025-21680 is a vulnerability in the Linux kernel's pktgen module that allows for out-of-bounds access to the pkt_dev->imix_entries array. This occurs when a user passes an excessive number of imix entries, leading to an invalid memory access due to improper boundary checks. The issue was identified by the Linux Verification Center and can result in system crashes or exploitation by malicious actors, potentially allowing them to execute arbitrary code.
How To Fix
Minimum fixed version
6.1.128-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can limit the number of imix entries passed to the pktgen module to avoid triggering the out-of-bounds access. This can be done by configuring the pktgen settings to use fewer entries until a patch is applied.
Conclusion
CVE-2025-21680 poses a significant risk to systems running the Linux kernel, particularly those utilizing the pktgen module. It is crucial for users to apply the necessary updates to protect their systems from potential exploitation. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
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FAQ
CVE-2025-21680 is a vulnerability in the Linux kernel's pktgen module that allows for out-of-bounds memory access, potentially leading to system crashes or exploitation.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The risks include system crashes, unauthorized access, and potential execution of arbitrary code by malicious actors.
Yes, a patch is available. Users should update their Linux kernel to the latest version to mitigate this vulnerability.
If an immediate update is not possible, limit the number of imix entries passed to the pktgen module as a temporary workaround.
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