The flaw resides in Transmute’s POST /api/files/url endpoint, which downloads the user‑supplied URL without validating that the resolved hostname is external or omitted of redirect protection. The HTTP downloader follows redirects without restrictions, allowing a caller to target internal or cloud‑bound endpoints. Because the retrieved content is stored and later returned to the requester, an attacker can extract arbitrary internal data, effectively performing a full‑read SSRF (CWE‑918).

Any installed Transmute version earlier than 1.3.0 is affected. All deployments that expose the API endpoint without implementing hostname or IP validation or a whitelist of destinations are vulnerable. The issue was fixed in the 1.3.0 release, so those versions and later are no longer exposed to this problem.

The CVSS score of 6.5 rates the vulnerability as moderate severity. The EPSS metric is not available, and it is not listed in the CISA KEV catalog. The SSRF path is straightforward: an attacker must submit a URL that resolves to an internal resource, and the server will fetch the contents and store it for later retrieval access if enabled, compromised or legitimate credentials are needed; however, no additional technical barrier limits exploitation. Consequently the risk of exploitation remains significant for configurations that expose the API and allow the vulnerable endpoint to be accessed.