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CVE Record

CVE-2026-31755: usb: cdns3: gadget: fix NULL pointer dereference in ep_queue

In the Linux kernel, the following vulnerability has been resolved: usb: cdns3: gadget: fix NULL pointer dereference in ep_queue When the gadget endpoint is disabled or not yet configured, the ep->desc pointer can be NULL. This leads to a NULL pointer dereference when __cdns3_gadget_ep_queue() is called, causing a kernel crash. Add a check to return -ESHUTDOWN if ep->desc is NULL, which is the standard return code for unconfigured endpoints. This prevents potential crashes when ep_queue is called on endpoints that are not ready.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2026-31755 is a Linux kernel crash bug in the Cadence USB3 gadget driver. If an endpoint is not configured or has been disabled, the kernel can dereference a NULL pointer and crash. This is primarily an availability risk for systems using the affected USB gadget functionality.

Executive priority

Treat as a targeted availability issue. Prioritize patching where Linux devices rely on USB gadget/device-mode functionality, especially embedded products or appliances. It is less urgent for systems without the affected driver path, and no active exploitation is reported in the provided sources.

Technical view

The issue is in the Linux kernel cdns3 gadget path, specifically __cdns3_gadget_ep_queue(). When ep->desc is NULL for an unconfigured or disabled endpoint, ep_queue can trigger a NULL pointer dereference. The upstream fix adds a NULL check and returns -ESHUTDOWN for unconfigured endpoints.

Likely exposure

Exposure appears limited to Linux systems using the cdns3 USB gadget driver and affected kernel builds. General Linux servers not using this USB gadget path may not be practically exposed. Confirm against vendor kernels, backports, and the listed stable commits.

Exploitation context

The sources describe a kernel crash condition, not privilege escalation or data exposure. CISA KEV status is false in the provided bundle, and no cited source reports active exploitation. Practical exploitability depends on access to trigger gadget endpoint queueing on affected systems.

Researcher notes

The record lacks CVSS, CWE, and detailed attack prerequisites. The fix behavior is clear: guard ep->desc and return -ESHUTDOWN. Researchers should focus on configuration-dependent reachability and vendor kernel backports rather than assuming all Linux deployments are equally exposed.

Mitigation direction

  • Update to a kernel containing the referenced stable cdns3 gadget fix.
  • Use distribution security advisories to identify backported fixed kernel packages.
  • If updates are delayed, review whether cdns3 USB gadget functionality can be disabled.
  • Prioritize embedded, appliance, and USB device-mode Linux systems first.

Validation and detection

  • Inventory Linux systems using Cadence cdns3 USB gadget support.
  • Compare running kernel packages with vendor fixed releases or referenced stable commits.
  • Check whether the cdns3 gadget driver is present and enabled.
  • Review kernel crash logs for NULL dereference in cdns3 gadget endpoint queueing.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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.

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CVE-2026-31755 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
3Timeline events
0ADP providers
9Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbe, 7733f6c32e36ff9d7adadf40001039bf219b1cbeunaffected
LinuxLinux5.4, 0, 5.10.260, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12, 7.0affected
Weakness

CWE details

No CWE listed

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