# Dex improper authorization in token-exchange endpoint

Source: https://junglewise.ai/threats/dex-improper-authorization-in-token-exchange-endpoint-f3b09e96  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

Severity: high · CVSS 8.7 · Published 2026-06-09

Dex is an identity service that uses 'connectors' to let users log in via different providers like Google or Okta. A security flaw in the token-exchange feature allows a client application to bypass administrator-defined restrictions on which login providers it is allowed to use. If a client's secret is leaked, an attacker could use it to obtain high-privilege identity tokens from unauthorized providers, potentially gaining access to sensitive production systems.

Technologies: [github.com/dexidp/dex (Go)](https://junglewise.ai/threats/technologies/github-com-dexidp-dex). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** High severity, with a CVSS score of 8.7, published 9 June 2026.

**Which products and versions are affected?** Dexidp Dex < 0.0.0-20260303131938-204dbb2e3ff7; github.com/dexidp/dex (Go) < 0.0.0-20260303131938-204dbb2e3ff7.

**Is there a fix for This vulnerability?** A patch was published on 2026-06-09: Fix reviewed and finalized in GitHub Advisory Database Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a software library.

**Am I affected?** Check whether you run Dexidp Dex or github.com/dexidp/dex (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The `handleTokenExchange` function in `server/handlers.go` fails to call `isConnectorAllowed` before issuing tokens, creating an authorization bypass. While other authentication flows correctly enforce the `AllowedConnectors` ACL defined in the client configuration, the token-exchange path only verifies that the connector exists and supports the grant type. An attacker with a leaked client secret and a valid token from a 'forbidden' connector can successfully exchange it for a Dex-signed token for that client. This allows for privilege escalation where a low-trust client can impersonate identities from high-trust connectors (e.g., Okta) that were explicitly restricted by policy. The vulnerability was introduced in the development branch and is fixed in commit 204dbb2.

## Affected products

- dexidp Dex < 0.0.0-20260303131938-204dbb2e3ff7

## Timeline

- 2026-03-03: other: Last unaffected stable release v2.45.1
- 2026-03-11: other: Vulnerability introduced in master branch via PR #4610
- 2026-05-20: disclosed: Advisory published by maintainers
- 2026-06-09: patched: Fix reviewed and finalized in GitHub Advisory Database

## References

- [https://api.github.com/users/matte1782](https://api.github.com/users/matte1782)
- [https://github.com/matte1782](https://github.com/matte1782)
- [https://api.github.com/users/matte1782/gists%7B/gist_id%7D](https://api.github.com/users/matte1782/gists%7B/gist_id%7D)
- [https://api.github.com/users/matte1782/repos](https://api.github.com/users/matte1782/repos)
- [https://avatars.githubusercontent.com/u/28739806?v=4](https://avatars.githubusercontent.com/u/28739806?v=4)
- [https://api.github.com/users/matte1782/events%7B/privacy%7D](https://api.github.com/users/matte1782/events%7B/privacy%7D)

## Related threats

- [GO-2026-5231 - Dex: Token-exchange endpoint is missing AllowedConnectors enforcement in github.com/dexidp/dex](https://junglewise.ai/threats/go-2026-5231-dex-token-exchange-endpoint-is-missing-allowedconnectors-d0d1b456)
- [GO-2024-2476 - Dex discarding TLSconfig and always serves deprecated TLS 1.0/1.1 and insecure ciphers in github.com/dexidp/dex](https://junglewise.ai/threats/cve-2024-23656-dex-discarding-tlsconfig-and-always-serves-deprecated-tls-1-0-1-1)
- [Dex vulnerable to Man-in-the-Middle allowing ID token capture via intercepted authorization code](https://junglewise.ai/threats/cve-2022-39222-dex-vulnerable-to-man-in-the-middle-allowing-id-token-capture-via)
- [Critical security issues in XML encoding in github.com/dexidp/dex](https://junglewise.ai/threats/cve-2020-26290-authentication-bypass-in-dex)