Vulnerability · Published Aug 4, 2026 · Assigned by redhat
CVE-2026-70367Stunnel: ssrf bypass in stunnel socks proxy via ipv4-mapped ipv6 loopback and unspecified addresses allows access to loopback-only services
Medium 5.4
In plain English
A medium-severity server-side request forgery in stunnel from Mobi-Com Polska Sp. z o.o.. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | stunnel | 5.82-r0 | ALPINE-CVE-2026-70367 |
| Debian:14 | stunnel | 3:5.80-1 | DEBIAN-CVE-2026-70367 |
| Debian:12 | stunnel4 | no fix listed | DEBIAN-CVE-2026-70367 |
| Debian:13 | stunnel4 | no fix listed | DEBIAN-CVE-2026-70367 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mobi-Com Polska Sp. z o.o. | stunnel | 5.25 – before 5.80 |
| Red Hat | Red Hat Enterprise Linux 10 | see references |
| Red Hat | Red Hat Enterprise Linux 6 | see references |
| Red Hat | Red Hat Enterprise Linux 7 | see references |
| Red Hat | Red Hat Enterprise Linux 8 | see references |
| Red Hat | Red Hat Enterprise Linux 9 | see references |
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
References
- https://access.redhat.com/security/cve/CVE-2026-70367 vdb-entry, x_refsource_REDHAT
- RHBZ#2462083 issue-tracking, x_refsource_REDHAT