CVE-2025-40255
In the Linux kernel, the following vulnerability has been resolved: net: core: prevent NULL deref in generic_hwtstamp_ioctl_lower() The ethtool tsconfig Netlink path can trigger a null pointer de…
Overview
CVE-2025-40255 is a known-severity vulnerability. It was published on December 4, 2025.
Technical description
In the Linux kernel, the following vulnerability has been resolved:
net: core: prevent NULL deref in generic_hwtstamp_ioctl_lower()
The ethtool tsconfig Netlink path can trigger a null pointer
dereference. A call chain such as:
tsconfig_prepare_data() ->
dev_get_hwtstamp_phylib() ->
vlan_hwtstamp_get() ->
generic_hwtstamp_get_lower() ->
generic_hwtstamp_ioctl_lower()
results in generic_hwtstamp_ioctl_lower() being called with
kernel_cfg->ifr as NULL.
The generic_hwtstamp_ioctl_lower() function does not expect
a NULL ifr and dereferences it, leading to a system crash.
Fix this by adding a NULL check for kernel_cfg->ifr in
generic_hwtstamp_ioctl_lower(). If ifr is NULL, return -EINVAL.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2025-40255?
CVE-2025-40255 is a known-severity vulnerability. It was published on December 4, 2025.
How severe is CVE-2025-40255?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2025-40255?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2025-40255?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-40255 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.