CVE-2024-23656 is a high-severity (CVSS 7.5) CWE-326 vulnerability in github.com/dexidp/dex. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for github.com/dexidp/dex — see the affected versions and patch details below.
Dex 2.37.0 is discarding TLSconfig and always serves deprecated TLS 1.0/1.1 and insecure ciphers
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-23656.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/dexidp/dex🐹github.com/dexidp/dexReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/dexidp/dex | ≥ 2.37.0&&< 2.38.0 | 2.38.0go get github.com/dexidp/dex@v2.38.0 |
| 🐹Go | github.com/dexidp/dex | all versions | 0.0.0-20240125115555-5bbdb4420254go get github.com/dexidp/dex@v0.0.0-20240125115555-5bbdb4420254 |
Affected Products
dexlinuxfoundationResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/dexidp/dex, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/dexidp/dex to 2.38.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-23656 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2024-23656 in your dependencies?
Find it across Go, including transitive dependencies.