Rekor is a software supply chain transparency log. In versions 1.4.3 and below, attackers can trigger SSRF to arbitrary internal services because /api/v1/index/retrieve supports retrieving a public key via user-provided URL. Since the SSRF only can trigger GET requests, the request cannot mutate state. The response from the GET request is not returned to the caller so data exfiltration is not possible. A malicious actor could attempt to probe an internal network through Blind SSRF. The issue has been fixed in version 1.5.0. To workaround this issue, disable the search endpoint with --enable_retrieve_api=false.