Server-Side Request Forgery Vulnerability in Stunnel by OpenSSL
CVE-2026-70367

5.4MEDIUM

Key Information:

Vendor

Red Hat
Status
Red Hat Enterprise Linux 10
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Vendor
CVE Published:
4 August 2026

What is CVE-2026-70367?

A Server-Side Request Forgery (SSRF) bypass vulnerability exists in Stunnel versions 5.79 and earlier when configured to operate in SOCKS proxy mode. This issue permits an attacker to bypass localhost restrictions, leveraging IPv4-mapped IPv6 addresses (like '::ffff:127.0.0.1') or unspecified addresses ('0.0.0.0', '::'). Consequently, this vulnerability allows unauthorized access to loopback-only services hosted on the Stunnel server.

References

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

CVSS V3.1

Score:
5.4
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

This issue was discovered by Found by AISLE in partnership with Red Hat.
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