{"id":"CVE-2024-23656","aliases":["GHSA-gr79-9v6v-gc9r","GO-2024-2476"],"url":"https://o3.security/vulnerability/CVE-2024-23656","summary":"Dex 2.37.0 is discarding TLSconfig and always serves deprecated TLS 1.0/1.1 and insecure ciphers","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<rest as default>\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.","published":"2024-01-25T19:45:41.237Z","modified":"2026-08-12T03:51:42.639718604Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"Go","name":"github.com/dexidp/dex","fixedVersion":"2.38.0"},{"ecosystem":"Go","name":"github.com/dexidp/dex","fixedVersion":"0.0.0-20240125115555-5bbdb4420254"}],"fix":{"url":"https://github.com/dexidp/dex/commit/5bbdb4420254ba73b9c4df4775fe7bdacf233b17","label":"dexidp/dex@5bbdb44"},"references":[{"type":"WEB","url":"https://github.com/dexidp/dex/blob/70d7a2c7c1bb2646b1a540e49616cbc39622fb83/cmd/dex/serve.go#L425"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/23xxx/CVE-2024-23656.json"},{"type":"ADVISORY","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":"REPORT","url":"https://github.com/dexidp/dex/issues/2848"},{"type":"FIX","url":"https://github.com/dexidp/dex/commit/5bbdb4420254ba73b9c4df4775fe7bdacf233b17"},{"type":"FIX","url":"https://github.com/dexidp/dex/pull/2964"},{"type":"PACKAGE","url":"https://github.com/dexidp/dex"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:42.639718604Z"}}