SAML authentication vulnerability due to stdlib XML parsing
Date: 2022-02
Affected: go/github.com/fleetdm/fleet/v4
Attack vector: other
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2020-26276
CWE: CWE-290

### Impact Due to issues in Go's standard library XML parsing, a valid SAML response may be mutated by an attacker to modify the trusted document. This can result in allowing unverified logins from a SAML IdP. Users that configure Fleet with SSO login may be vulnerable to this issue. ### Patches This issue is patched in 3.5.1 using https://github.com/mattermost/xml-roundtrip-validator. ### Workarounds If upgrade to 3.5.1 is not possible, users should disable SSO authentication in Fleet. ### References See https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities/ for more information about the underlying vulnerabilities. ### For more information If you have any questions or comments about this advisory: * Email us at [security@fleetdm.com](mailto:security@fleetdm.com) * Join #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)


Mitigations:

Architectural layers (MAESTRO):