# CVE-2026-46043: RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv

> An integer underflow in the Linux kernel RDMA driver allows attackers to cause a denial of service via crafted packets.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-88455, BELL-CVE-2026-46043, DEBIAN-CVE-2026-46043, GHSA-ww3w-m544-ppj6, ROOT-OS-DEBIAN-11-CVE-2026-46043, ROOT-OS-DEBIAN-12-CVE-2026-46043, ROOT-OS-UBUNTU-2204-CVE-2026-46043, ROOT-OS-UBUNTU-2404-CVE-2026-46043, UBUNTU-CVE-2026-46043

## What is CVE-2026-46043?

CVE-2026-46043 is a critical vulnerability in Linux kernel, published on 27 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv

rxe_rcv() currently checks only that the incoming packet is at least
header_size(pkt) bytes long before payload_size() is used.

However, payload_size() subtracts both the attacker-controlled BTH pad
field and RXE_ICRC_SIZE from pkt->paylen:

  payload_size = pkt->paylen - offset[RXE_PAYLOAD] - bth_pad(pkt)
                 - RXE_ICRC_SIZE

This means a short packet can still make payload_size() underflow even
if it includes enough bytes for the fixed headers. Simply requiring
header_size(pkt) + RXE_ICRC_SIZE is not sufficient either, because a
packet with a forged non-zero BTH pad can still leave payload_size()
negative and pass an underflowed value to later receive-path users.

Fix this by validating pkt->paylen against the full minimum length
required by payload_size(): header_size(pkt) + bth_pad(pkt) +
RXE_ICRC_SIZE.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-46043?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46043?

Apply the vendor's patch.

## Is CVE-2026-46043 being exploited?

There is no known exploitation of CVE-2026-46043 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46043 and fix it if it is affected.

What it is: CVE-2026-46043 is a critical vulnerability in Linux kernel, published on 27 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46043 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46043/ (Markdown: https://insights.sbomify.com/CVE-2026-46043/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46043
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46043
- OSV: https://osv.dev/vulnerability/CVE-2026-46043

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46043/
Summaries are generated and may contain mistakes; the official description above is the record.