CVE-2020-27847

A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation. This flaw allows an attacker to bypass SAML authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. This flaw affects dex versions before 2.27.0.

### Impact The following vulnerabilities have been disclosed, which impact users leveraging the SAML connector: Signature Validation Bypass (CVE-2020-15216): https://github.com/russellhaering/goxmldsig/security/advisories/GHSA-q547-gmf8-8jr7 `encoding/xml` instabilities: - [Element namespace prefix instability (CVE-2020-29511)](https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-elements.md) - [Attribute namespace prefix instability (CVE-2020-29509)](https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-attributes.md) - [Directive comment instability (CVE-2020-29510)](https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-directives.md) ### Patches Immediately update to [Dex v2.27.0](https://github.com/dexidp/dex/releases/tag/v2.27.0). ### Workarounds There are no known workarounds.

Dex is a federated OpenID Connect provider written in Go. In Dex before version 2.27.0 there is a critical set of vulnerabilities which impacts users leveraging the SAML connector. The vulnerabilities enables potential signature bypass due to issues with XML encoding in the underlying Go library. The vulnerabilities have been addressed in version 2.27.0 by using the xml-roundtrip-validator from Mattermost (see related references).