CVE-2025-21793

Local service interruption via zero dummy buswidth

Published Feb 27, 2025 · Updated May 11, 2026

Divide-by-zero in the Linux kernel's Socionext F_OSPI driver allows local users to interrupt service via a no-dummy-cycle SPI-NOR command. The f_ospi_get_dummy_cycle() function divides the dummy-byte bit count by op->dummy.buswidth without handling the case in which both values are zero. Exploitation requires local low-privileged access and a system using the Socionext F_OSPI controller; the documented result is an availability-impacting CPU warning.

CVSS severity5.5
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide-by-zero in the Linux kernel's Socionext F_OSPI driver allows local users to interrupt service via a no-dummy-cycle SPI-NOR command. The f_ospi_get_dummy_cycle() function divides the dummy-byte bit count by op->dummy.buswidth without handling the case in which both values are zero. Exploitation requires local low-privileged access and a system using the Socionext F_OSPI controller; the documented result is an availability-impacting CPU warning.

The record

CVE
CVE-2025-21793
Published
Feb 27, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-369, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1b74dd64c8612619e399e5a31da79a3636914495 <3588b1c0fde2f58d166e3f94a5a58d64b893526c
  2. Affected versionversion=1b74dd64c8612619e399e5a31da79a3636914495 <4df6f005bef04a3dd16c028124a1b5684db3922b
  3. Affected versionversion=1b74dd64c8612619e399e5a31da79a3636914495 <7434135553bc03809a55803ee6a8dcaae6240d55
  4. Affected versionversion=1b74dd64c8612619e399e5a31da79a3636914495 <966328191b4c389c0f2159fa242915f51cbc1679
  5. Affected versionversion=6.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1b74dd64c8612619e399e5a31da79a3636914495 <3588b1c0fde2f58d166e3f94a5a58d64b893526c; version=1b74dd64c8612619e399e5a31da79a3636914495 <4df6f005bef04a3dd16c028124a1b5684db3922b; version=1b74dd64c8612619e399e5a31da79a3636914495 <7434135553bc03809a55803ee6a8dcaae6240d55; version=1b74dd64c8612619e399e5a31da79a3636914495 <966328191b4c389c0f2159fa242915f51cbc1679; version=6.2

Published CVSS scores

5.5CISACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-369Divide By Zero
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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