Omni: Operator can traverse image-factory API paths via unsanitized `talos_version` in CreateSchematic

Summary

managementServer.CreateSchematic (internal/backend/grpc/schematics.go) passes the caller-controlled TalosVersion field directly to imageFactoryClient.OverlaysVersions, which embeds it verbatim into a fmt.Sprintf("/version/%s/overlays/official", talosVersion) path template. url.URL.JoinPath resolves any ../ sequences in that path, allowing an authenticated Operator to rewrite the URL path and force Omni to issue HTTP GET requests to unintended paths on the configured image-factory server. Error body content from those unintended endpoints is returned to the caller.

Severity

• Attack Vector: Network: exploited via the gRPC CreateSchematic API endpoint.
• Attack Complexity: Low: once the attacker holds an Operator credential and has identified a media ID with an overlay, exploitation is a single API call.
• Privileges Required: High: role.Operator is required, which has administrative capabilities on Omni.
• User Interaction: None.
• Scope: Unchanged: the traversal is constrained to the configured image-factory host; the attacker cannot redirect Omni to an arbitrary external server.
• Confidentiality Impact: Low: error body content from unintended image-factory endpoints is reflected back to the operator, potentially leaking server-internal information.
• Integrity Impact: None: only HTTP GET requests are issued; no write operations are performed.
• Availability Impact: None.

Impact

• Same-host path traversal: An authenticated Operator can force Omni to issue GET requests to arbitrary URL paths on the configured image-factory server, bypassing the intended versioned overlay API structure.
• Error-body disclosure: HTTP error responses from unintended image-factory endpoints are reflected back to the operator, potentially leaking server-internal diagnostics or sensitive path content.
• Internal network probing: In deployments using a private image-factory instance on an internal network, the attacker can probe endpoint existence and partial responses through error-text differences.
• Depth control: By varying the number of ../ prefixes in talosVersion, the attacker can reach any path hierarchy on the image-factory host.