What’s Vulnerable › Vulnerabilities
CVE-2020-26290: Critical security issues in XML encoding in Dex
- Severity: critical (CVSS 9.6 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 1.0% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2020-12-28 · updated 2026-06-17
- Weakness: CWE-347
Description
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).
Affected products
- dexidp dex: before 2.27.0 — fixed in 2.27.0
How to fix
Upgrade to a fixed version: dexidp dex 2.27.0. Check the vendor advisory for mitigations.
References
- https://github.com/dexidp/dex/commit/324b1c886b407594196113a3dbddebe38eecd4e8
- https://github.com/dexidp/dex/releases/tag/v2.27.0
- https://github.com/dexidp/dex/security/advisories/GHSA-m9hp-7r99-94h5
- https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-attributes.md
- https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-directives.md
- https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-elements.md
- https://github.com/russellhaering/goxmldsig/security/advisories/GHSA-q547-gmf8-8jr7
- https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities/
- https://github.com/dexidp/dex/commit/324b1c886b407594196113a3dbddebe38eecd4e8
- https://github.com/dexidp/dex/releases/tag/v2.27.0
- https://github.com/dexidp/dex/security/advisories/GHSA-m9hp-7r99-94h5
- https://github.com/mattermost/xml-roundtrip-validator/blob/master/advisories/unstable-attributes.md
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