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Fencer Vulns
critical 9.8

CVE-2020-27847 json

A vulnerability exists in the SAML connector of the github.com/dexidp/dex library used to process SAML Signature Validation.

published 2021-05-28 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-2428

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 77%
public exploits
0
none known

Summary

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.

Patch / fix

  • linuxfoundation dex 2.27.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-27847 updated cvss 3.9

dexidp/dex: authentication bypass in saml authentication

  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/observatorium-rhel8
    affected: no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.72% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • n/a dexidp/dex

Classification

Weakness
  • CWE-228 Improper Handling of Syntactically Invalid Structure

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.