Medium [CVE-2026-70367] SSRF bypass in stunnel SOCKS proxy via IPv4-mapped IPv6 loopback and unspecified addresses allows access to loopback-only services
This medium-severity Red Hat Linux advisory covers CVE-2026-70367; related products: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
SSRF bypass in stunnel SOCKS proxy via IPv4-mapped IPv6 loopback and unspecified addresses allows access to loopback-only services. Red Hat rates this moderate (CVSS 5.4).
Weakness: CWE-918.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- To mitigate this issue, if SOCKS proxying functionality is not required, disable the "protocol = socks" configuration in "stunnel". If SOCKS proxying is necessary, restrict access to the SOCKS listener by binding it to a trusted management network or localhost, and enforce client authentication or network ACL controls. Run "stunnel" in a container or network namespace where no other services are bound to localhost, or add firewall rules to restrict outgoing connections from "stunnel" to localhost.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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