CVE-2026-54777: CoreWCF.NetNamedPipe CoreWCF NetNamedPipe Transport Accepts Attach Vulnerability

MODERATE
Advisory Identifier: GHSA-6jj2-4q5c-x8g6
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CVSS 6.5
CWE-367 CWE-665
Published
Advisory Summary

CVE-2026-54777 is a MODERATE (CVSS 6.5) corewcf netnamedpipe transport accepts attach vulnerability (CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition) affecting CoreWCF.NetNamedPipe libraries in the NuGet ecosystem. The issue involves corewcf netnamedpipe transport accepts attach to a pre-existing named pipe instance. Remediation is available by upgrading affected packages to version 1.8.1, 1.9.1.

CVE-2026-54777 at a Glance

CVE Identifier CVE-2026-54777
GHSA Identifier GHSA-6jj2-4q5c-x8g6
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
Affected Product CoreWCF.NetNamedPipe
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L).

Attack Vector Local (AV:L)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-54777

To remediate this vulnerability, upgrade all affected CoreWCF.NetNamedPipe dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

CoreWCF.NetNamedPipe fixed: 1.8.1 
Upgrade CoreWCF.NetNamedPipe to 1.8.1
CoreWCF.NetNamedPipe fixed: 1.9.1 
Upgrade CoreWCF.NetNamedPipe to 1.9.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for CoreWCF.NetNamedPipe

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-54777, inspect your project dependencies for CoreWCF.NetNamedPipe:

inspect dependencies for CoreWCF.NetNamedPipe

Analyze the terminal output to locate any version of CoreWCF.NetNamedPipe in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.8.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition, where the product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. In CoreWCF.NetNamedPipe, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact CoreWCF NetNamedPipe transport accepts attach to a pre-existing named pipe instance, allowing local interception of NetNamedPipe traffic. NetNamedPipe creates a shared memory object based on the listening url, then generated a unique GUID for the named pipe it will be using and saves this to the shared memory object. Then it creates the named pipe to listen for clients. This requires an attacker to race the service and create the named pipe between the service publishing the GUID to the shared memory location (which the attacker needs to read) and the service creating the named pipe itself. ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds None

CVE-2026-54777 Affected CoreWCF.NetNamedPipe Versions

2 component(s)
Fixed Versions:
1.8.11.9.1
Product / Package Ecosystem Affected Versions Fixed Version
CoreWCF.NetNamedPipe
nuget/CoreWCF.NetNamedPipe
NuGet
< 1.8.1
1.8.1
CoreWCF.NetNamedPipe
nuget/CoreWCF.NetNamedPipe
NuGet
≥ 1.9.0
< 1.9.1
1.9.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-6jj2-4q5c-x8g6
CoreWCF.NetNamedPipe Source Repository REPOSITORY
https://github.com/CoreWCF/CoreWCF

Frequently Asked Questions

What is CVE-2026-54777?
CVE-2026-54777 is a security vulnerability in CoreWCF.NetNamedPipe involving CoreWCF NetNamedPipe transport accepts attach to a pre-existing named pipe instance under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition.
Which CoreWCF.NetNamedPipe versions are affected?
Affected versions include releases prior to 1.8.1, 1.9.1 across affected packages: CoreWCF.NetNamedPipe.
What version fixes CVE-2026-54777?
Upgrading to 1.8.1, 1.9.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is CoreWCF.NetNamedPipe affected?
Yes, CoreWCF.NetNamedPipe is affected in releases prior to 1.8.1, 1.9.1. Upgrade your dependency to 1.8.1, 1.9.1 or later.
What is the CVSS score of CVE-2026-54777?
CVE-2026-54777 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L.
What CWE is associated with CVE-2026-54777?
CVE-2026-54777 is classified under CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition (The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.).
How can I check NuGet dependencies for CVE-2026-54777?
Run the dependency tree command: 'inspect dependencies for CoreWCF.NetNamedPipe'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6jj2-4q5c-x8g6",
  "modified" : "2026-06-19T20:46:55Z",
  "published" : "2026-06-19T20:46:55Z",
  "aliases" : [ "CVE-2026-54777" ],
  "summary" : "CoreWCF NetNamedPipe transport accepts attach to a pre-existing named pipe instance",
  "details" : "### Impact\nCoreWCF NetNamedPipe transport accepts attach to a pre-existing named pipe instance, allowing local interception of NetNamedPipe traffic. NetNamedPipe creates a shared memory object based on the listening url, then generated a unique GUID for the named pipe it will be using and saves this to the shared memory object. Then it creates the named pipe to listen for clients. This requires an attacker to race the service and create the named pipe between the service publishing the GUID to the shared memory location (which the attacker needs to read) and the service creating the named pipe itself.\n\n### Patches\nFixed in CoreWCF v1.8.1 and v1.9.1\n\n### Workarounds\nNone",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CoreWCF.NetNamedPipe"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.8.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CoreWCF.NetNamedPipe"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.9.0"
      }, {
        "fixed" : "1.9.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-6jj2-4q5c-x8g6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/CoreWCF/CoreWCF"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-367", "CWE-665" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-19T20:46:55Z",
    "nvd_published_at" : null
  }
}