CVE-2020-26276

Fleet is an open source osquery manager. In Fleet before version 3.5.1, due to issues in Gos 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. This issue is patched in 3.5.1. The fix was made using https://github.com/mattermost/xml-roundtrip-validator If upgrade to 3.5.1 is not possible, users should disable SSO authentication in Fleet.

Weakness

This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.

Affected Software

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/21.html
• https://cwe.mitre.org/data/definitions/22.html
• https://cwe.mitre.org/data/definitions/459.html
• https://cwe.mitre.org/data/definitions/461.html
• https://cwe.mitre.org/data/definitions/473.html
• https://cwe.mitre.org/data/definitions/476.html
• https://cwe.mitre.org/data/definitions/59.html
• https://cwe.mitre.org/data/definitions/60.html
• https://cwe.mitre.org/data/definitions/667.html
• https://cwe.mitre.org/data/definitions/94.html

References

• https://github.com/fleetdm/fleet/blob/master/CHANGELOG.md#fleet-351-dec-14-2020
• https://github.com/fleetdm/fleet/commit/57812a532e5f749c8e18c6f6a652eca65c083607
• https://github.com/fleetdm/fleet/security/advisories/GHSA-w3wf-cfx3-6gcx
• https://github.com/mattermost/xml-roundtrip-validator
• https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities