CVE-2026-54783: Signature Bypass (CVSS 7.4)

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.

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CVSS v3.1 Score

7.4

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-294 CWE-294

CWE-345 CWE-345

CWE-347 CWE-347

References

Other References

https://github.com/CoreWCF/CoreWCF/commit/0589692d4b9a41d21b34ac48281e95f6df7f4ce5 https://github.com/CoreWCF/CoreWCF/commit/30aef805270976c42477e3f2a05f4e563d86e247 https://github.com/CoreWCF/CoreWCF/commit/4618f24165ad018ad3ed2636bf8c3bc87d2a3be2 https://github.com/CoreWCF/CoreWCF/releases/tag/v1.8.1 https://github.com/CoreWCF/CoreWCF/releases/tag/v1.9.1 https://github.com/CoreWCF/CoreWCF/security/advisories/GHSA-gqv6-pwcg-87r8

Frequently Asked Questions

What is CVE-2026-54783? +

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. It has a CVSS v3.1 base score of 7.4 (HIGH).

How severe is CVE-2026-54783? +

CVE-2026-54783 has a CVSS v3.1 score of 7.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-54783? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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