Description
In the Linux kernel, the following vulnerability has been resolved:

net: usb: cdc_ncm: add ndpoffset to NDP16 nframes bounds check

cdc_ncm_rx_verify_ndp16() validates that the NDP header and its DPE
entries fit within the skb. The first check correctly accounts for
ndpoffset:

if ((ndpoffset + sizeof(struct usb_cdc_ncm_ndp16)) > skb_in->len)

but the second check omits it:

if ((sizeof(struct usb_cdc_ncm_ndp16) +
ret * (sizeof(struct usb_cdc_ncm_dpe16))) > skb_in->len)

This validates the DPE array size against the total skb length as if
the NDP were at offset 0, rather than at ndpoffset. When the NDP is
placed near the end of the NTB (large wNdpIndex), the DPE entries can
extend past the skb data buffer even though the check passes.
cdc_ncm_rx_fixup() then reads out-of-bounds memory when iterating
the DPE array.

Add ndpoffset to the nframes bounds check and use struct_size_t() to
express the NDP-plus-DPE-array size more clearly.
Published: 2026-04-03
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The Linux kernel’s CDC NCM driver performs an improper validation of the Network Data Packet (NDP) header and its Data Packet Entry (DPE) array. When the NDP is located near the end of the Non‑Temporal Buffer (NTB), the driver checks only the NDP size but neglects the offset before validating the DPE array size. This mis‑calculation can allow memory reads beyond the end of the packet buffer, exposing kernel memory contents. The out‑of‑bounds read occurs during packet processing and can result in information disclosure or a crash.

Affected Systems

All Linux kernel builds that enable the CDC‑NCM USB network interface are affected. The vulnerability is present in any kernel revision prior to the commit that corrected the bounds check; specific upstream version ranges are not listed in the advisory.

Risk and Exploitability

The CVSS score of 7.8 indicates high severity, while the EPSS score of less than 1% and absence from the CISA KEV catalog suggest low exploitation likelihood. The flaw requires the attacker to supply a malicious USB packet to a device presenting a CDC‑NCM interface. Based on the description, it is inferred that this may require local or physically trusted access rather than a purely remote exploit. Even if exploited, the impact is limited to memory disclosure or local denial of service, without privilege escalation.

Generated by OpenCVE AI on May 21, 2026 at 01:51 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update the Linux kernel to a release that includes the corrected bounds check for the CDC‑NCM driver.
  • If a timely kernel upgrade is not possible, permanently disable the CDC‑NCM module by removing the module from the boot configuration or adding a blacklist entry.
  • Alternatively, restrict USB CDC‑NCM devices using udev rules to prevent the driver from loading for those devices.
  • Monitor kernel mailing lists and vendor advisories for any additional recommendations or stop‑gap measures.

Generated by OpenCVE AI on May 21, 2026 at 01:51 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DSA Debian DSA DSA-6238-1 linux security update
History

Thu, 21 May 2026 00:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-129
CPEs cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Tue, 07 Apr 2026 08:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-125
CWE-400

Sat, 04 Apr 2026 01:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1285
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Fri, 03 Apr 2026 21:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-125
CWE-400

Fri, 03 Apr 2026 16:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net: usb: cdc_ncm: add ndpoffset to NDP16 nframes bounds check cdc_ncm_rx_verify_ndp16() validates that the NDP header and its DPE entries fit within the skb. The first check correctly accounts for ndpoffset: if ((ndpoffset + sizeof(struct usb_cdc_ncm_ndp16)) > skb_in->len) but the second check omits it: if ((sizeof(struct usb_cdc_ncm_ndp16) + ret * (sizeof(struct usb_cdc_ncm_dpe16))) > skb_in->len) This validates the DPE array size against the total skb length as if the NDP were at offset 0, rather than at ndpoffset. When the NDP is placed near the end of the NTB (large wNdpIndex), the DPE entries can extend past the skb data buffer even though the check passes. cdc_ncm_rx_fixup() then reads out-of-bounds memory when iterating the DPE array. Add ndpoffset to the nframes bounds check and use struct_size_t() to express the NDP-plus-DPE-array size more clearly.
Title net: usb: cdc_ncm: add ndpoffset to NDP16 nframes bounds check
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T22:07:10.252Z

Reserved: 2026-01-13T15:37:46.020Z

Link: CVE-2026-23448

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-04-03T16:16:30.863

Modified: 2026-05-21T00:44:10.273

Link: CVE-2026-23448

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-03T00:00:00Z

Links: CVE-2026-23448 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-21T02:00:11Z

Weaknesses