CVE-2026-54778 CoreWCF: UnixDomainSocket Non-Reentrant POSIX Identity Resolution
Concurrent connections in CoreWCF UnixDomainSocket identity resolution can cause identity misattribution or host crashes due to non-reentrant system calls.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54778?
CVE-2026-54778 is a medium-severity vulnerability in CoreWCF, published on 8 Jul 2026. It can only be exploited from the same machine or local 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, CoreWCF UnixDomainSocket POSIX peer identity resolution uses non-reentrant getpwuid and getgrgid calls, allowing concurrent connections to attribute one connection's identity to another or crash the host process under contention. This issue is fixed in versions 1.8.1 and 1.9.1.
Which versions are affected by CVE-2026-54778?
4 open source packages ship an affected version, including CoreWCF.UnixDomainSocket.
| Package | Affected | Fixed in |
|---|---|---|
CoreWCF.UnixDomainSocket NuGet | All versions | 1.8.1 |
CoreWCF.UnixDomainSocket NuGet | All versions | 1.8.1 |
CoreWCF.UnixDomainSocket NuGet | From 1.9.0 | 1.9.1 |
CoreWCF.UnixDomainSocket NuGet | From 1.9.0 | 1.9.1 |
How do I fix CVE-2026-54778?
Upgrade CoreWCF.UnixDomainSocket to a fixed version for your release line: 1.8.1 or 1.9.1.
Is CVE-2026-54778 being exploited?
There is no known exploitation of CVE-2026-54778 in the wild and no public exploit code.
Sources
Also known as GHSA-q6v9-43v5-jv9q.