CVE-2025-39921
5.5 · MEDIUMOverview
CVE-2025-39921 is a medium-severity vulnerability affecting linux linux_kernel. It was published on October 1, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
Technical Description
In the Linux kernel, the following vulnerability has been resolved:
spi: microchip-core-qspi: stop checking viability of op->max_freq in supports_op callback
In commit 13529647743d9 ("spi: microchip-core-qspi: Support per spi-mem
operation frequency switches") the logic for checking the viability of
op->max_freq in mchp_coreqspi_setup_clock() was copied into
mchp_coreqspi_supports_op(). Unfortunately, op->max_freq is not valid
when this function is called during probe but is instead zero.
Accordingly, baud_rate_val is calculated to be INT_MAX due to division
by zero, causing probe of the attached memory device to fail.
Seemingly spi-microchip-core-qspi was the only driver that had such a
modification made to its supports_op callback when the per_op_freq
capability was added, so just remove it to restore prior functionality.
Remediation
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. 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.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linux | linux_kernel | >= 6.14, < 6.16.6 | Affected |
Frequently Asked Questions
What is CVE-2025-39921?
CVE-2025-39921 is a medium-severity vulnerability affecting linux linux_kernel. It was published on October 1, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2025-39921?
This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2025-39921?
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. 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-2025-39921?
CyberStrike's AI-powered security agents can automatically detect CVE-2025-39921 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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