CVE-2026-54783 CoreWCF: XML Signature Wrapping in WS-Security endorsing/supporting signature verification allows replay of captured signed messages
Attackers can replay captured signed SOAP messages to execute arbitrary service operations as the victim due to improper signature verification in CoreWCF.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54783?
CVE-2026-54783 is a high-severity authentication bypass vulnerability in CoreWCF, published on 8 Jul 2026. An attacker can exploit it over the internet without logging in, 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, 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.
Which versions are affected by CVE-2026-54783?
4 open source packages ship an affected version, including CoreWCF.Primitives.
| Package | Affected | Fixed in |
|---|---|---|
CoreWCF.Primitives NuGet | All versions | 1.8.1 |
CoreWCF.Primitives NuGet | All versions | 1.8.1 |
CoreWCF.Primitives NuGet | From 1.9.0 | 1.9.1 |
CoreWCF.Primitives NuGet | From 1.9.0 | 1.9.1 |
How do I fix CVE-2026-54783?
Upgrade CoreWCF.Primitives to a fixed version for your release line: 1.8.1 or 1.9.1.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-54783 being exploited?
There is no known exploitation of CVE-2026-54783 in the wild and no public exploit code.
Sources
Also known as GHSA-gqv6-pwcg-87r8.