CoreWCF: WS-Security signature substitution via document-wide Signature lookup

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-54773: 0.37% estimated exploitation activity in the next 30 days; percentile 30.93 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact An unauthenticated remote attacker who can place a SOAP header lexically before wsse:Security can embed a ds:Signature of their choosing inside that header and cause the server to verify the attacker-supplied signature instead of the one carried in the security header. Preconditions Exploitation requires the endpoint be configured with an endorsing supporting token binding, and the attacker constructs a ds:Signature whose KeyInfo resolves through the receive-side token resolver to a key under the attacker’s control. Both are conditions outside the attacker’s direct control on a generic deployment. Patches Fixed in CoreWCF v1.8.1 and v1.9.1 Workarounds Use a security token resolver that only accepts references to issuer-pinned X.509 chains (the default when expecting a static set of signing certificates).

Published by the source

19 Jun 2026, 20:46 UTC

Last modified by the source

19 Jun 2026, 20:46 UTC

Source last checked

26 Oct 2026, 17:04 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-jc6x-rj79-w4mx

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-54773

Advisory: CoreWCF: WS-Security signature substitution via document-wide Signature lookup
IDs: CVE-2026-54773, GHSA-jc6x-rj79-w4mx
Record: https://patchnext.com/advisories/cve-2026-54773 (revision 1, source checked 26 Oct 2026, 17:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: corewcf.primitives 1.9.1, 1.8.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet corewcf.primitives: affected < 1.8.1; >= 1.9.0, < 1.9.1; fixed in 1.8.1, 1.9.1

## Suggested inspection (read-only)
- NuGet corewcf.primitives: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on corewcf.primitives.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jc6x-rj79-w4mx (GitHub-reviewed advisory GHSA-jc6x-rj79-w4mx lists affected ranges: NuGet corewcf.primitives >=0 =1.9.0 <1.9.1)

Commands are suggestions: review each one before running it.