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GHSA-GR79-9V6V-GC9R

Vulnerability from github – Published: 2024-01-26 01:57 – Updated: 2025-05-27 15:45
VLAI
Summary
Dex discarding TLSconfig and always serves deprecated TLS 1.0/1.1 and insecure ciphers
Details

Summary

Dex 2.37.0 is serving HTTPS with insecure TLS 1.0 and TLS 1.1.

Details

While working on https://github.com/dexidp/dex/issues/2848 and implementing configurable TLS support, I noticed my changes did not have any effect in TLS config, so I started investigating.

https://github.com/dexidp/dex/blob/70d7a2c7c1bb2646b1a540e49616cbc39622fb83/cmd/dex/serve.go#L425 is seemingly setting TLS 1.2 as minimum version, but the whole tlsConfig is ignored after "TLS cert reloader" was introduced in https://github.com/dexidp/dex/pull/2964. Configured cipher suites are not respected either, as seen on the output.

PoC

Build Dex, generate certs with gencert.sh, modify config.dev.yaml to run on https, using generated certs.

issuer: http://127.0.0.1:5556/dex

storage:
  type: sqlite3
  config:
    file: dex.db

web:
  https: 127.0.0.1:5556
  tlsCert: examples/k8s/ssl/cert.pem
  tlsKey: examples/k8s/ssl/key.pem

<rest as default>

Run dex bin/dex serve config.dev.yaml.

Install sslyze, easy to use SSL connection analyzer:

pip3 install sslyze
sslyze 127.0.0.1:5556

In Dex 2.37.0, TLS 1.0 and TLS 1.1 are enabled in addition to expected TLS 1.2 and TLS 1.3.

 * TLS 1.0 Cipher Suites:
     Attempted to connect using 80 cipher suites.

     The server accepted the following 6 cipher suites:
        TLS_RSA_WITH_AES_256_CBC_SHA                      256                      
        TLS_RSA_WITH_AES_128_CBC_SHA                      128                      
        TLS_RSA_WITH_3DES_EDE_CBC_SHA                     168                      
        TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                256       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                128       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA               168       ECDH: prime256v1 (256 bits)

     The group of cipher suites supported by the server has the following properties:
       Forward Secrecy                    OK - Supported
       Legacy RC4 Algorithm               OK - Not Supported


 * TLS 1.1 Cipher Suites:
     Attempted to connect using 80 cipher suites.

     The server accepted the following 6 cipher suites:
        TLS_RSA_WITH_AES_256_CBC_SHA                      256                      
        TLS_RSA_WITH_AES_128_CBC_SHA                      128                      
        TLS_RSA_WITH_3DES_EDE_CBC_SHA                     168                      
        TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                256       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                128       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA               168       ECDH: prime256v1 (256 bits)

     The group of cipher suites supported by the server has the following properties:
       Forward Secrecy                    OK - Supported
       Legacy RC4 Algorithm               OK - Not Supported


 * TLS 1.2 Cipher Suites:
     Attempted to connect using 156 cipher suites.

     The server accepted the following 11 cipher suites:
        TLS_RSA_WITH_AES_256_GCM_SHA384                   256                      
        TLS_RSA_WITH_AES_256_CBC_SHA                      256                      
        TLS_RSA_WITH_AES_128_GCM_SHA256                   128                      
        TLS_RSA_WITH_AES_128_CBC_SHA                      128                      
        TLS_RSA_WITH_3DES_EDE_CBC_SHA                     168                      
        TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256       256       ECDH: X25519 (253 bits)
        TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384             256       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                256       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256             128       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                128       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA               168       ECDH: prime256v1 (256 bits)

     The group of cipher suites supported by the server has the following properties:
       Forward Secrecy                    OK - Supported
       Legacy RC4 Algorithm               OK - Not Supported


 * TLS 1.3 Cipher Suites:
     Attempted to connect using 5 cipher suites.

     The server accepted the following 3 cipher suites:
        TLS_CHACHA20_POLY1305_SHA256                      256       ECDH: X25519 (253 bits)
        TLS_AES_256_GCM_SHA384                            256       ECDH: X25519 (253 bits)
        TLS_AES_128_GCM_SHA256                            128       ECDH: X25519 (253 bits)

In Dex 2.36.0, TLS 1.0 and TLS 1.1 are disabled as expected.

 * TLS 1.0 Cipher Suites:
     Attempted to connect using 80 cipher suites; the server rejected all cipher suites.

 * TLS 1.1 Cipher Suites:
     Attempted to connect using 80 cipher suites; the server rejected all cipher suites.

 * TLS 1.2 Cipher Suites:
     Attempted to connect using 156 cipher suites.

     The server accepted the following 5 cipher suites:
        TLS_RSA_WITH_AES_256_GCM_SHA384                   256                      
        TLS_RSA_WITH_AES_128_GCM_SHA256                   128                      
        TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256       256       ECDH: X25519 (253 bits)
        TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384             256       ECDH: prime256v1 (256 bits)
        TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256             128       ECDH: prime256v1 (256 bits)

     The group of cipher suites supported by the server has the following properties:
       Forward Secrecy                    OK - Supported
       Legacy RC4 Algorithm               OK - Not Supported


 * TLS 1.3 Cipher Suites:
     Attempted to connect using 5 cipher suites.

     The server accepted the following 3 cipher suites:
        TLS_CHACHA20_POLY1305_SHA256                      256       ECDH: X25519 (253 bits)
        TLS_AES_256_GCM_SHA384                            256       ECDH: X25519 (253 bits)

Impact

TLS 1.0 and TLS 1.1 connections can be decrypted by the attacker, and hence decrypt the traffic to Dex.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/dexidp/dex"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.37.0"
            },
            {
              "fixed": "2.38.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.37.0"
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/dexidp/dex"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.0-20240125115555-5bbdb4420254"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-23656"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-326"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-01-26T01:57:31Z",
    "nvd_published_at": "2024-01-25T20:15:41Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\nDex 2.37.0 is serving HTTPS with insecure TLS 1.0 and TLS 1.1.\n\n\n### Details\nWhile working on https://github.com/dexidp/dex/issues/2848 and implementing configurable TLS support, I noticed my changes did not have any effect in TLS config, so I started investigating. \n\nhttps://github.com/dexidp/dex/blob/70d7a2c7c1bb2646b1a540e49616cbc39622fb83/cmd/dex/serve.go#L425 is seemingly setting TLS 1.2 as minimum version, but the whole tlsConfig is ignored after \"TLS cert reloader\" was introduced in https://github.com/dexidp/dex/pull/2964. Configured cipher suites are not respected either, as seen on the output.\n\n### PoC\nBuild Dex, generate certs with `gencert.sh`, modify `config.dev.yaml` to run on https, using generated certs.\n\n```console\nissuer: http://127.0.0.1:5556/dex\n\nstorage:\n  type: sqlite3\n  config:\n    file: dex.db\n\nweb:\n  https: 127.0.0.1:5556\n  tlsCert: examples/k8s/ssl/cert.pem\n  tlsKey: examples/k8s/ssl/key.pem\n\n\u003crest as default\u003e\n```\n\nRun dex `bin/dex serve config.dev.yaml`.\n\nInstall `sslyze`, easy to use SSL connection analyzer:\n\n```console\npip3 install sslyze\nsslyze 127.0.0.1:5556\n```\n\nIn Dex 2.37.0, TLS 1.0 and TLS 1.1 are enabled in addition to expected TLS 1.2 and TLS 1.3.\n```console\n * TLS 1.0 Cipher Suites:\n     Attempted to connect using 80 cipher suites.\n\n     The server accepted the following 6 cipher suites:\n        TLS_RSA_WITH_AES_256_CBC_SHA                      256                      \n        TLS_RSA_WITH_AES_128_CBC_SHA                      128                      \n        TLS_RSA_WITH_3DES_EDE_CBC_SHA                     168                      \n        TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                256       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                128       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA               168       ECDH: prime256v1 (256 bits)\n\n     The group of cipher suites supported by the server has the following properties:\n       Forward Secrecy                    OK - Supported\n       Legacy RC4 Algorithm               OK - Not Supported\n\n\n * TLS 1.1 Cipher Suites:\n     Attempted to connect using 80 cipher suites.\n\n     The server accepted the following 6 cipher suites:\n        TLS_RSA_WITH_AES_256_CBC_SHA                      256                      \n        TLS_RSA_WITH_AES_128_CBC_SHA                      128                      \n        TLS_RSA_WITH_3DES_EDE_CBC_SHA                     168                      \n        TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                256       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                128       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA               168       ECDH: prime256v1 (256 bits)\n\n     The group of cipher suites supported by the server has the following properties:\n       Forward Secrecy                    OK - Supported\n       Legacy RC4 Algorithm               OK - Not Supported\n\n\n * TLS 1.2 Cipher Suites:\n     Attempted to connect using 156 cipher suites.\n\n     The server accepted the following 11 cipher suites:\n        TLS_RSA_WITH_AES_256_GCM_SHA384                   256                      \n        TLS_RSA_WITH_AES_256_CBC_SHA                      256                      \n        TLS_RSA_WITH_AES_128_GCM_SHA256                   128                      \n        TLS_RSA_WITH_AES_128_CBC_SHA                      128                      \n        TLS_RSA_WITH_3DES_EDE_CBC_SHA                     168                      \n        TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256       256       ECDH: X25519 (253 bits)\n        TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384             256       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                256       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256             128       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA                128       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA               168       ECDH: prime256v1 (256 bits)\n\n     The group of cipher suites supported by the server has the following properties:\n       Forward Secrecy                    OK - Supported\n       Legacy RC4 Algorithm               OK - Not Supported\n\n\n * TLS 1.3 Cipher Suites:\n     Attempted to connect using 5 cipher suites.\n\n     The server accepted the following 3 cipher suites:\n        TLS_CHACHA20_POLY1305_SHA256                      256       ECDH: X25519 (253 bits)\n        TLS_AES_256_GCM_SHA384                            256       ECDH: X25519 (253 bits)\n        TLS_AES_128_GCM_SHA256                            128       ECDH: X25519 (253 bits)\n```\n\nIn Dex 2.36.0, TLS 1.0 and TLS 1.1 are disabled as expected.\n```console\n * TLS 1.0 Cipher Suites:\n     Attempted to connect using 80 cipher suites; the server rejected all cipher suites.\n\n * TLS 1.1 Cipher Suites:\n     Attempted to connect using 80 cipher suites; the server rejected all cipher suites.\n\n * TLS 1.2 Cipher Suites:\n     Attempted to connect using 156 cipher suites.\n\n     The server accepted the following 5 cipher suites:\n        TLS_RSA_WITH_AES_256_GCM_SHA384                   256                      \n        TLS_RSA_WITH_AES_128_GCM_SHA256                   128                      \n        TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256       256       ECDH: X25519 (253 bits)\n        TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384             256       ECDH: prime256v1 (256 bits)\n        TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256             128       ECDH: prime256v1 (256 bits)\n\n     The group of cipher suites supported by the server has the following properties:\n       Forward Secrecy                    OK - Supported\n       Legacy RC4 Algorithm               OK - Not Supported\n\n\n * TLS 1.3 Cipher Suites:\n     Attempted to connect using 5 cipher suites.\n\n     The server accepted the following 3 cipher suites:\n        TLS_CHACHA20_POLY1305_SHA256                      256       ECDH: X25519 (253 bits)\n        TLS_AES_256_GCM_SHA384                            256       ECDH: X25519 (253 bits)\n```\n\n### Impact\nTLS 1.0 and TLS 1.1 connections can be decrypted by the attacker, and hence decrypt the traffic to Dex.",
  "id": "GHSA-gr79-9v6v-gc9r",
  "modified": "2025-05-27T15:45:13Z",
  "published": "2024-01-26T01:57:31Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/dexidp/dex/security/advisories/GHSA-gr79-9v6v-gc9r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-23656"
    },
    {
      "type": "WEB",
      "url": "https://github.com/dexidp/dex/issues/2848"
    },
    {
      "type": "WEB",
      "url": "https://github.com/dexidp/dex/pull/2964"
    },
    {
      "type": "WEB",
      "url": "https://github.com/dexidp/dex/commit/5bbdb4420254ba73b9c4df4775fe7bdacf233b17"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/dexidp/dex"
    },
    {
      "type": "WEB",
      "url": "https://github.com/dexidp/dex/blob/70d7a2c7c1bb2646b1a540e49616cbc39622fb83/cmd/dex/serve.go#L425"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Dex discarding TLSconfig and always serves deprecated TLS 1.0/1.1 and insecure ciphers"
}



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