# CVE-2026-74378: RDMA/rxe: Fix TOCTOU heap overflow in get_srq_wqe

> A race condition in the Linux kernel RDMA driver allows local attackers to trigger a heap overflow, potentially leading to code execution or privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-74378, DEBIAN-CVE-2026-74378, GHSA-7vv8-3m2v-67j6, UBUNTU-CVE-2026-74378

## What is CVE-2026-74378?

CVE-2026-74378 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

## Which versions are affected by CVE-2026-74378?


## How do I fix CVE-2026-74378?

Apply the vendor's patch.

## Is CVE-2026-74378 being exploited?

There is no known exploitation of CVE-2026-74378 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74378 and fix it if it is affected.

What it is: CVE-2026-74378 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74378 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-74378/ (Markdown: https://insights.sbomify.com/CVE-2026-74378/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74378
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74378
- OSV: https://osv.dev/vulnerability/CVE-2026-74378

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74378/
Summaries are generated and may contain mistakes; the official description above is the record.