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CVE-2026-70367

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

Published: Aug 4, 2026Updated: Aug 6, 2026 Sources: CVE List NVDCWE-918
5.4MEDIUM
NVD MITRE
EPSS Score
0.2%
Top 94.8%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Workaround Only
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-918

Affected Products

Mobi-Com Polska Sp. z o.o.
stunnel
Red Hat
commercial·US
Red Hat Enterprise Linux 10On-premOS
Operating Systems / linux-distro
and 4 more affected products View all →

Exploitability

Workaround Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Command and Control
Initial Access
View detailed technique mapping

References

https://access.redhat.com/security/cve/CVE-2026-70367
access.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2462083
bugzilla.redhat.com

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