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CVE-2020-26290

Critical security issues in XML encoding in Dex

9.3 CriticalFix available

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).

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.99%Down 0.9 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 9.3

Critical security issues in XML encoding in Dex

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).

Record
CVE-2020-26290
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
EUVDEUVD-2021-2551 9.3

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).

Record
EUVD-2021-2551
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-m9hp-7r99-94h5 9.3

Critical security issues in XML encoding in github.com/dexidp/dex

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:

Patches

Immediately update to Dex v2.27.0.

Workarounds

There are no known workarounds.

Record
GHSA-m9hp-7r99-94h5
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
NVD 9.3

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).

Record
CVE-2020-26290
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CVSS 2.0
6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness
CWE-347
Updated
2026-11-02
OSV 9.6

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).

Record
CVE-2020-26290
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVCVE-2020-27847 9.8

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.

Record
CVE-2020-27847
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-2x32-jm95-2cpx 9.8

Authentication Bypass in dex

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.

Record
GHSA-2x32-jm95-2cpx
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-228, CWE-290
Updated
2026-11-02
OSVGHSA-m9hp-7r99-94h5 9.3

Critical security issues in XML encoding in github.com/dexidp/dex

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:

Patches

Immediately update to Dex v2.27.0.

Workarounds

There are no known workarounds.

Record
GHSA-m9hp-7r99-94h5
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Weakness
CWE-347
Updated
2026-11-02
OSVopenSUSE-SU-2024:10714-1 No score

dex-oidc-2.28.1-1.3 on GA media

These are all security issues fixed in the dex-oidc-2.28.1-1.3 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10714-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/dexidp/dex
Go
before 2.27.0
2.27.0
github.com/russellhaering/goxmldsig
Go
before 1.1.0
1.1.0
github.com/dexidp/dex
Go
From an advisory covering 2 CVEs
before 2.27.0
2.27.0
github.com/russellhaering/goxmldsig
Go
From an advisory covering 2 CVEs
before 1.1.0
1.1.0
dex-oidc
openSUSE:Tumbleweed
before 2.28.1-1.3
2.28.1-1.3

History

History
RecordedChangedSources
affected, facts
aliases, productsEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-26290 is a critical vulnerability (CVSS 9.3) in Dexidp Dex, published December 28, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.99%, the 62nd percentile. Fixed in github.com/dexidp/dex 2.27.0.

References

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