CVE-2025-39921: Linux kernel · spi: microchip-core-qspi: stop checking viability of op->max_freq in supports_op
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 5.5 Medium · fixed in ac8a13f35d5b8996582b3f97b924838a5c570c18 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:18 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-01-14.
- Patch
- Available – fixed in ac8a13f35d5b8996582b3f97b924838a5c570c18, 89e7353f522f5cf70cb48c01ce2dcdcb275b8022, 4ad071e3d57967f7ab483aed0687468bc1d9e9ce
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade Linux kernel to ac8a13f35d5b8996582b3f97b924838a5c570c18, 89e7353f522f5cf70cb48c01ce2dcdcb275b8022 or 4ad071e3d57967f7ab483aed0687468bc1d9e9ce.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
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.