CVE-2026-68368

Summary

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

usb: gadget: f_ncm: validate datagram bounds in ncm_unwrap_ntb()

When unpacking host-supplied NTBs, ncm_unwrap_ntb() checks datagram length against frame_max but does not verify that the datagram fits within the declared block length. Additionally, when decoding multiple NTBs from a single socket buffer, subsequent block lengths are not checked against the actual remaining buffer data.

With these checks missing, a malicious USB host can specify datagram offsets and lengths that point beyond the block, or supply secondary NTB headers declaring lengths larger than the buffer. skb_put_data() then copies adjacent kernel memory from skb_shared_info into the network skb.

Fix this by verifying that sufficient buffer space remains for the NTB header before parsing, handling zero-length block declarations, ensuring that block lengths never exceed the remaining buffer space, and verifying that each datagram payload stays strictly within the block boundary.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/e07751d0527ccc2a1c32eb0b0b7da3b4b9b5381f
• https://git.kernel.org/stable/c/fff1059d139ef798bab917990524faaf25854ca8
• https://git.kernel.org/stable/c/40c706a0224bde194667e3378c689b542fec4b44
• https://git.kernel.org/stable/c/41fd5f2fb0027d3773ae949e3247c2e0a2a7fe5c
• https://git.kernel.org/stable/c/1febec7e47cdcd01f43fb0211094e3010474666e

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