Skipper vulnerable to SSRF via X-Skipper-Proxy

Impact

Skipper prior to version v0.13.236 is vulnerable to server-side request forgery (SSRF). An attacker can exploit a vulnerable version of proxy to access the internal metadata server or other unauthenticated URLs by adding an specific header (X-Skipper-Proxy) to the http request.

Patches

The problem was patched in version https://github.com/zalando/skipper/releases/tag/v0.13.237.
Users need to upgrade to skipper >=v0.13.237.

Workarounds

Use dropRequestHeader("X-Skipper-Proxy") filter

References

https://github.com/zalando/skipper/releases/tag/v0.13.237

For more information

If you have any questions or comments about this advisory:

• Open an issue in https://github.com/zalando/skipper/issues/new/choose
• Chat with us in slack: https://app.slack.com/client/T029RQSE6/C82Q5JNH5