CVE-2026-54773
CoreWCF: WS-Security signature substitution via document-wide Signature lookup
Description
### 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).
How to fix CVE-2026-54773
To remediate CVE-2026-54773, upgrade the affected package to a fixed version below.
- —upgrade to 1.8.1 or later
Is CVE-2026-54773 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-54773.
Affected packages (1)
- from 0, < 1.8.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N |