The endpoint /v1/upload/sbom in PIA accepts a bearer JWT and checks its unverified iss claim against an allowlist using Python's urlparse. Because urlparse and the OIDC discovery library parse an authority string containing a backslash into different hostnames, an attacker can forge an issuer that passes the allowlist check but causes the discovery routine to resolve to a host of the attacker’s choosing. This flaw is a Server Side Request Forgery that allows an unauthenticated user to trigger outbound requests from the PIA server to arbitrary hosts, potentially exfiltrating data, reaching internal services, or performing other malicious actions.

The affected product is Eclipse CSI PIA. No specific version information is disclosed. All installations of PIA that expose the POST /v1/upload/sbom endpoint are potentially impacted.

The vulnerability has a CVSS score of 8.8, indicating high severity. The EPSS score is below 1%, implying a low probability of exploit in the wild, and the flaw is not currently listed in CISA’s KEV catalog. An attacker can exploit the flaw without authentication by sending a crafted request to the upload endpoint with a JWT containing a specially formatted iss claim. The flaw does not require privileged access or complex conditions, making it tractable for an attacker with network connectivity to the PIA service.