Steve doesn’t verify a server’s certificate and is susceptible to man-in-the-middle (MitM) attacks

### Impact A vulnerability has been identified in Steve where by default it was using an insecure option that did not validate the certificate presented by the remote server while performing a TLS connection. This could allow the execution of a man-in-the-middle (MitM) attack against services using Steve. For example, Rancher relies on Steve as a dependency for its user interface (UI) to proxy requests to Kubernetes clusters. Users who have the permission to create a service in Rancher’s local cluster can take over Rancher’s UI and display their own UI to gather sensitive information. This is only possible when the setting `ui-offline-preferred` is manually set to `remote` (by default Rancher sets it to `dynamic`). This enables further attacks such as cross-site scripting (XSS), or tampering the UI to collect passwords from other users etc. Please consult the associated [MITRE ATT&CK - Technique - Adversary-in-the-Middle](https://attack.mitre.org/techniques/T1557/) for further information about this category of attack. ### Patches Patched versions of Steve include releases `v0.2.1`, `v0.3.3`, `v0.4.4` and `v0.5.13`. This vulnerability is addressed by changing Steve to always verify a server’s certificate based on Go’s TLS settings. ### Workarounds If you can't upgrade to a fixed version, please make sure that you are only using Steve to connect to trusted servers. ### References If you have any questions or comments about this advisory: - Reach out to the [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries. - Open an issue in the [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository. - Verify with our [support matrix](https://www.suse.com/suse-rancher/support-matrix/all-supported-versions/) and [product support lifecycle](https://www.suse.com/lifecycle/).

Source published

25 Apr 2025 15:12:44 UTC

Source modified

10 Sep 2026 03:50:23 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Publisher rating · HIGH