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Fencer Vulns
medium 6.5

CVE-2026-54777 json

CoreWCF NetNamedPipe transport accepts attach to a pre-existing named pipe instance

published 2026-06-19 4 mo ago modified 2026-07-10 4 mo ago also EUVD-2026-42447 , GHSA-6jj2-4q5c-x8g6

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

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 NetNamedPipe transport accepts attachment to a pre-existing named pipe instance, allowing local interception of NetNamedPipe traffic when an attacker races NamedPipeListener startup between shared memory GUID publication and service named pipe creation. This issue is fixed in versions 1.8.1 and 1.9.1.

Patch / fix

  • nuget CoreWCF.NetNamedPipe 1.8.1, 1.9.1
  • corewcf corewcf 1.8.1, 1.9.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
GitHub 3.1 6.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L

Affected packages

ecosystem package affected fixed in
nuget CoreWCF.NetNamedPipe
<1.8.1
>=1.9.0, <1.9.1
1.8.1
1.9.1

Affected products

  • CoreWCF CoreWCF

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition
  • CWE-665 Improper Initialization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.