# CVE-2026-68425: IB/mad: Drop unmatched RMPP responses before reassembly

> An attacker can cause a denial of service in the Linux kernel by sending unsolicited InfiniBand RMPP responses that trigger unnecessary state allocation before validation.

- **Severity:** High 7.1 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-68425, DEBIAN-CVE-2026-68425, GHSA-c7q4-7jj2-g2jh, UBUNTU-CVE-2026-68425

## What is CVE-2026-68425?

CVE-2026-68425 is a high-severity denial of service vulnerability in Linux, published on 10 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:

IB/mad: Drop unmatched RMPP responses before reassembly

Kernel-handled RMPP receive processing starts reassembly for active
DATA responses before the response is matched to an outstanding send.
The normal match happens later, after ib_process_rmpp_recv_wc() has
either assembled a complete message or consumed the segment.

That ordering lets an unsolicited response that routes to a kernel
RMPP agent by the high TID bits allocate or extend RMPP receive state
before the full TID and source address are checked against a real
request. A reordered burst can therefore reach the receive-side
insertion path even though the response would not match any send.

For kernel-handled RMPP DATA responses, require the existing
ib_find_send_mad() match before entering RMPP reassembly. The matcher
already checks the full TID, management class and source address/GID
against the agent wait, backlog and in-flight send lists. If there is
no match, drop the response without creating RMPP state.

This leaves the RMPP window behavior unchanged and only rejects
responses that have no corresponding request.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-68425?


## How do I fix CVE-2026-68425?

Apply the vendor's patch.

## Is CVE-2026-68425 being exploited?

There is no known exploitation of CVE-2026-68425 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68425 and fix it if it is affected.

What it is: CVE-2026-68425 is a high-severity denial of service vulnerability in Linux, published on 10 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-2026-68425 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-2026-68425/ (Markdown: https://insights.sbomify.com/CVE-2026-68425/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68425
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68425
- OSV: https://osv.dev/vulnerability/CVE-2026-68425

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68425/
Summaries are generated and may contain mistakes; the official description above is the record.