CVE-2026-54774
CoreWCF: SamlSerializer skips SignatureValue verification when SAML signing token is not an X.509 certificate
Description
### Impact When a service is configured to validate SAML tokens using a method other than X.509 certificate signing, the final signature verification is skipped. #### Preconditions The service is configured to authenticate using SAML tokens and an out of band token resolver (commonly the IssuerTokenResolver of IssuedTokenServiceCredential) holds a non-X.509 SecurityToken whose key identifier the attacker can reference in the assertion’s `<KeyInfo>` - for example a `BinarySecretSecurityToken` representing the symmetric proof key issued by a WS-Trust symmetric-key holder-of-key STS. ### Patches Fixed in CoreWCF v1.8.1 and v1.9.1 ### Workarounds None
How to fix CVE-2026-54774
To remediate CVE-2026-54774, upgrade the affected package to a fixed version below.
- —upgrade to 1.8.1 or later
Is CVE-2026-54774 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-54774.
Affected packages (1)
- from 0, < 1.8.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |