Security readout for executives and security teams
Plain-English summary
CVE-2025-21793 is a Linux kernel flaw where a specific SPI flash driver can hit a divide-by-zero condition. The stated impact is availability, not data theft or privilege escalation. It requires local access with low privileges, so urgency is higher for exposed multi-user or embedded systems using this driver.
Executive priority
Treat as a routine but real availability risk. Prioritize patching for embedded, appliance, or shared Linux systems that use the affected SPI flash driver. It is not currently supported by evidence of internet-scale exploitation or data compromise.
Technical view
The Linux kernel sn-f-ospi SPI NOR driver could divide by zero when a command has no dummy cycles, making both dummy bus cycle bytes and width zero. The kernel fix avoids that calculation and returns zero. CVSS 3.1 is 5.5: local attack vector, low complexity, low privileges, no user interaction, high availability impact.
Likely exposure
Exposure appears limited to Linux systems running affected kernel versions and using the sn-f-ospi SPI NOR driver path. The source lists Linux kernel versions and stable kernel commits, but distribution-specific affected and fixed package versions are not provided in the bundle.
Exploitation context
No active exploitation is indicated; this CVE is not listed as KEV in the provided data. Exploitation would require local access with low privileges and conditions that trigger the affected driver calculation. The documented consequence is an availability impact from a divide-by-zero condition.
Researcher notes
This is CWE-369, division by zero, in a kernel driver. The CVE record and commit messages describe a defensive fix for no-dummy-cycle SPI NOR commands. Version applicability needs careful validation against kernel trees and vendor backports because distro package status is not included.
Mitigation direction
- Upgrade to a Linux kernel or distro package containing the referenced stable fixes.
- Prioritize systems using the sn-f-ospi SPI NOR driver or matching embedded hardware.
- Check Linux distribution advisories for exact affected and fixed package versions.
- If patching is delayed, consult vendor guidance for safe operational mitigations.
Validation and detection
- Inventory Linux kernel versions across servers, appliances, and embedded devices.
- Identify systems loading or built with the sn-f-ospi driver.
- Compare installed kernel packages against distribution advisories for CVE-2025-21793.
- Confirm the referenced stable commits are included in deployed kernel source or package changelogs.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-369: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-21793 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/966328191b4c389c0f2159fa242915f51cbc1679CVE reference, Linux
- https://git.kernel.org/stable/c/4df6f005bef04a3dd16c028124a1b5684db3922bCVE reference, Linux
- https://git.kernel.org/stable/c/7434135553bc03809a55803ee6a8dcaae6240d55CVE reference, Linux
- https://git.kernel.org/stable/c/3588b1c0fde2f58d166e3f94a5a58d64b893526cCVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Divide By Zero
Divide By Zero represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.