# CVE-2026-54780 — CoreWCF

> As of 2026-07-09, CVE-2026-54780 is a LOW-severity vulnerability in CoreWCF, CVSS v3.1 3.7, EPSS 0.1% (5.2th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-54780 as of 2026-07-09; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-07-09

## What is CVE-2026-54780?

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, the CoreWCF WS-Security 1.0 receive pipeline validates ds:SignedInfo SignatureMethod against the configured SecurityAlgorithmSuite but does not validate each ds:Reference DigestMethod, allowing a sender to use a rejected digest algorithm such as SHA-1 while the message is still accepted. This issue is fixed in versions 1.8.1 and 1.9.1.

The record classifies CVE-2026-54780 under weakness classes [CWE-327](https://intel.threadlinqs.com/cwe/CWE-327), [CWE-757](https://cwe.mitre.org/data/definitions/757.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 89 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 3.7 — LOW (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 5.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 2.1/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-08, last modified 2026-07-09

## Is CVE-2026-54780 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [CoreWCF](https://intel.threadlinqs.com/vendors/corewcf): CoreWCF

## How to fix CVE-2026-54780

No vendor patch reference has been recorded for CVE-2026-54780 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-54780

No threat campaign in the Threadlinqs corpus currently references CVE-2026-54780, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-07-12. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-4v55-cpmv-3vcm)

**Other references**

- [github.com](https://github.com/CoreWCF/CoreWCF/commit/58742312117cc671e6e9c694c2f5f9f669c17136)
- [github.com (9104e581cff3d047ace5e179bfae86807a44be1f)](https://github.com/CoreWCF/CoreWCF/commit/9104e581cff3d047ace5e179bfae86807a44be1f)
- [github.com (fea67b2cd73a5a85115c325d504303ec7382e133)](https://github.com/CoreWCF/CoreWCF/commit/fea67b2cd73a5a85115c325d504303ec7382e133)
- [github.com (v1.8)](https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1)
- [github.com (v1.9)](https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-54780
Full detection coverage and IOCs for threats exploiting CVE-2026-54780 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp