# CVE-2026-54775: CoreWCF: Kafka consume pump halts permanently on a Kafka tombstone (null-value record), causing persistent endpoint denial of service.

> An attacker with produce permissions can cause a permanent denial of service in CoreWCF services by sending a null-value Kafka record.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Jul 2026
- **Updated:** 9 Jul 2026
- **Also known as:** GHSA-m744-jhq9-ppw6

## What is CVE-2026-54775?

CVE-2026-54775 is a medium-severity denial of service vulnerability in CoreWCF, published on 8 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

CoreWCF is a port of the service side of Windows Communication Foundation (WCF) to .NET Core. Prior to 1.8.1 and 1.9.1, a CoreWCF service listening on a Kafka topic stops processing new records from that topic when KafkaTransportPump receives a null-value tombstone record, causing a persistent endpoint denial of service for attackers with produce permission. This issue is fixed in versions 1.8.1 and 1.9.1.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-754 (Improper Check for Unusual or Exceptional Conditions), CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2026-54775?

4 open source packages ship an affected version, including CoreWCF.Kafka.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `CoreWCF.Kafka` | NuGet | All versions | 1.8.1 |
| `CoreWCF.Kafka` | NuGet | All versions | 1.8.1 |
| `CoreWCF.Kafka` | NuGet | From 1.9.0 | 1.9.1 |
| `CoreWCF.Kafka` | NuGet | From 1.9.0 | 1.9.1 |

## How do I fix CVE-2026-54775?

Upgrade CoreWCF.Kafka to a fixed version for your release line: 1.8.1 or 1.9.1.

## Is CVE-2026-54775 being exploited?

There is no known exploitation of CVE-2026-54775 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54775 and fix it if it is affected.

What it is: CVE-2026-54775 is a medium-severity denial of service vulnerability in CoreWCF, published on 8 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54775 in the wild and no public exploit code.

Affected packages and fixed versions:
- CoreWCF.Kafka (NuGet): affected all versions; fixed in 1.8.1
- CoreWCF.Kafka (NuGet): affected all versions; fixed in 1.8.1
- CoreWCF.Kafka (NuGet): affected from 1.9.0; fixed in 1.9.1
- CoreWCF.Kafka (NuGet): affected from 1.9.0; fixed in 1.9.1

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-2026-54775/ (Markdown: https://insights.sbomify.com/CVE-2026-54775/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54775
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54775
- OSV: https://osv.dev/vulnerability/CVE-2026-54775

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54775/
Summaries are generated and may contain mistakes; the official description above is the record.