CVE-2019-20894: Github.com/traefik/traefik/v2 Improper Authentication Vulnerability

HIGH
Advisory Identifier: GHSA-q9mp-79cp-9g8j
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CVSS 7.5
CWE-287 CWE-295
Published
Advisory Summary

CVE-2019-20894 is a HIGH (CVSS 7.5) improper authentication vulnerability (CWE-287: Improper Authentication) affecting Github.com/traefik/traefik/v2 libraries in the Go ecosystem. The issue involves improper authentication. Remediation is available by upgrading affected packages to version 2.2.2.

CVE-2019-20894 at a Glance

CVE Identifier CVE-2019-20894
GHSA Identifier GHSA-q9mp-79cp-9g8j
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-287: Improper Authentication
Affected Product Github.com/traefik/traefik/v2
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2019-20894

To remediate this vulnerability, upgrade all affected Github.com/traefik/traefik/v2 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/traefik/traefik/v2 fixed: 2.2.2 
Upgrade github.com/traefik/traefik/v2 to 2.2.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/traefik/traefik/v2

How to Check if You Are Affected

To determine whether your application is affected by CVE-2019-20894, inspect your project dependencies for Github.com/traefik/traefik/v2:

inspect dependencies for github.com/traefik/traefik/v2

Analyze the terminal output to locate any version of Github.com/traefik/traefik/v2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.2.2), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In Github.com/traefik/traefik/v2, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Traefik 2.x, in certain configurations, allows HTTPS sessions to proceed without mutual TLS verification in a situation where ERR_BAD_SSL_CLIENT_AUTH_CERT should have occurred.

CVE-2019-20894 Affected Github.com/traefik/traefik/v2 Versions

1 component(s)
Fixed Versions:
2.2.2
Product / Package Ecosystem Affected Versions Fixed Version
github.com/traefik/traefik/v2
golang/github.com/traefik/traefik/v2
Go
< 2.2.2
2.2.2

References

NVD — CVE-2019-20894 NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-20894
Github.com/traefik/traefik/v2 Source Repository REPOSITORY
https://github.com/containous/traefik/issues/5312
Github.com/traefik/traefik/v2 Source Repository REPOSITORY
https://github.com/containous/traefik/pull/7008
Security Fix Commit FIX COMMIT
https://github.com/containous/traefik/commit/2b353971696717e980521b0e4baa1eba66c8d2bf

Frequently Asked Questions

What is CVE-2019-20894?
CVE-2019-20894 is a security vulnerability in Github.com/traefik/traefik/v2 involving Improper Authentication under CWE-287: Improper Authentication.
Which Github.com/traefik/traefik/v2 versions are affected?
Affected versions include releases prior to 2.2.2 across affected packages: github.com/traefik/traefik/v2.
What version fixes CVE-2019-20894?
Upgrading to 2.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/traefik/traefik/v2 affected?
Yes, github.com/traefik/traefik/v2 is affected in releases prior to 2.2.2. Upgrade your dependency to 2.2.2 or later.
What is the CVSS score of CVE-2019-20894?
CVE-2019-20894 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2019-20894?
CVE-2019-20894 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check Go dependencies for CVE-2019-20894?
Run the dependency tree command: 'inspect dependencies for github.com/traefik/traefik/v2'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q9mp-79cp-9g8j",
  "modified" : "2021-08-02T22:18:22Z",
  "published" : "2021-09-02T22:00:09Z",
  "aliases" : [ "CVE-2019-20894" ],
  "summary" : "Improper Authentication",
  "details" : "Traefik 2.x, in certain configurations, allows HTTPS sessions to proceed without mutual TLS verification in a situation where ERR_BAD_SSL_CLIENT_AUTH_CERT should have occurred.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/traefik/traefik/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2019-20894"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/containous/traefik/issues/5312"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/containous/traefik/pull/7008"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/containous/traefik/commit/2b353971696717e980521b0e4baa1eba66c8d2bf"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287", "CWE-295" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-02T22:18:22Z",
    "nvd_published_at" : "2020-07-02T16:15:00Z"
  }
}