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5.4 Medium

CVE-2026-70367 Stunnel: ssrf bypass in stunnel socks proxy via ipv4-mapped ipv6 loopback and unspecified addresses allows access to loopback-only services

Description

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.

CVSS 3.1 detail

Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Exploitable remotely over the network, with an ordinary account and without any user action; the impact on data or service is limited.

Attack vector
Network
Attack complexity
Low
Privileges required
Low
Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

Affected products and versions

Product Affected versions Fixed in
Red Hat Enterprise Linux 10 Versions not published
Red Hat Enterprise Linux 6 Versions not published
Red Hat Enterprise Linux 7 Versions not published
Red Hat Enterprise Linux 8 Versions not published
Red Hat Enterprise Linux 9 Versions not published
stunnel 5.25 5.25 → < 5.80 5.80

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