CVE-2026-68368 PUBLISHED

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

Assigner: Linux
Reserved: 30.07.2026 Published: 10.08.2026 Updated: 10.08.2026

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.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 to e07751d0527ccc2a1c32eb0b0b7da3b4b9b5381f (excl.)
  • affected from 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 to fff1059d139ef798bab917990524faaf25854ca8 (excl.)
  • affected from 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 to 40c706a0224bde194667e3378c689b542fec4b44 (excl.)
  • affected from 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 to 41fd5f2fb0027d3773ae949e3247c2e0a2a7fe5c (excl.)
  • affected from 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 to 1febec7e47cdcd01f43fb0211094e3010474666e (excl.)
  • Version f7e0611e207d8908c4f2858e244370529a76dbf7 is affected
  • Version b88ad6e714284b33a47834f5f2a294c2b37c66aa is affected
  • Version 471b23586387a32857778c511be60ab31c98dcfd is affected
  • Version 4f529c4d1e436230d3af7c09a3239677a14d2b46 is affected
  • Version ae6a5394d9fbe118bc95cfe376d6a9d91d7547e8 is affected
  • Version 5bdf93a2f5459f944b416b188178ca4a92fd206f is affected
  • Version ff3ba016263ee93a1c6209bf5ab1599de7ab1512 is affected
  • Version e7ca00f35d8a17af1ae19d529193ebc21bfda164 is affected
  • affected from 4.9.235 to 4.10 (excl.)
  • affected from 4.14.196 to 4.15 (excl.)
  • affected from 4.19.143 to 4.20 (excl.)
  • affected from 5.4.62 to 5.5 (excl.)
  • affected from 5.8.6 to 5.9 (excl.)
  • affected from 4.14.328 to 4.15 (excl.)
  • affected from 4.19.297 to 4.20 (excl.)
  • affected from 5.4.259 to 5.5 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 5.9 is affected
  • unaffected from 0 to 5.9 (excl.)
  • unaffected from 6.6.148 to 6.6.* (incl.)
  • unaffected from 6.12.101 to 6.12.* (incl.)
  • unaffected from 6.18.42 to 6.18.* (incl.)
  • unaffected from 7.1.6 to 7.1.* (incl.)
  • unaffected from 7.2-rc5 to * (incl.)

References