A Server-Side Request Forgery (SSRF) bypass vulnerability exists in “stunnel” 5.79 and lower when configured in SOCKS proxy mode. This flaw allows a client to bypass intended localhost restrictions by using IPv4-mapped IPv6 addresses (e.g., “::ffff:127.0.0.1”) or unspecified addresses ("0.0.0.0", "::"), enabling access to loopback-only services on the "stunnel" host that should not be network-reachable.
| Version | Type | Source | Base | Exp | Imp |
|---|---|---|---|---|---|
| 3.1 | Primary | NVD | 5.4 | 2.8 | 2.5 |
| 3.1 | Primary | cve.org | 5.4 | — | — |
| 3.1 | Primary | cve.org | 5.4 | — | — |
| 3.1 | Secondary | ENISA EUVD | 5.4 | — | — |
| 3.1 | Secondary | NVD | 5.4 | 2.8 | 2.5 |