{"id":"CVE-2026-70367","state":"PUBLISHED","title":"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.","publishedAt":"2026-08-04T13:52:20.527Z","updatedAt":"2026-08-06T07:28:08.760Z","severity":{"score":5.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","source":"redhat"},"assigner":"redhat","products":["Mobi-Com Polska Sp. z o.o. stunnel","Red Hat Red Hat Enterprise Linux 10","Red Hat Red Hat Enterprise Linux 6","Red Hat Red Hat Enterprise Linux 7","Red Hat Red Hat Enterprise Linux 8","Red Hat Red Hat Enterprise Linux 9"],"affected":[{"vendor":"Mobi-Com Polska Sp. z o.o.","product":"stunnel","defaultStatus":"unaffected","versions":[{"version":"5.25","status":"affected","lessThan":"5.80","versionType":"custom"}],"repo":"https://github.com/mtrojnar/stunnel"},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","packageName":"stunnel","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","packageName":"stunnel","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","packageName":"stunnel","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","packageName":"stunnel","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","packageName":"stunnel","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:9"]}],"references":["https://access.redhat.com/security/cve/CVE-2026-70367","https://bugzilla.redhat.com/show_bug.cgi?id=2462083"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/70xxx/CVE-2026-70367.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-70367","state":"PUBLISHED","datePublished":"2026-08-04T13:52:20.527Z","dateUpdated":"2026-08-06T07:28:08.760Z","assignerShortName":"redhat","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateReserved":"2026-08-04T07:03:23.572Z"},"containers":{"cna":{"title":"Stunnel: ssrf bypass in stunnel socks proxy via ipv4-mapped ipv6 loopback and unspecified addresses allows access to loopback-only services","descriptions":[{"lang":"en","value":"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":[{"vendor":"Mobi-Com Polska Sp. z o.o.","product":"stunnel","defaultStatus":"unaffected","versions":[{"version":"5.25","status":"affected","lessThan":"5.80","versionType":"custom"}],"repo":"https://github.com/mtrojnar/stunnel"},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","packageName":"stunnel","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","packageName":"stunnel","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","packageName":"stunnel","defaultStatus":"unaffected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","packageName":"stunnel","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","packageName":"stunnel","defaultStatus":"affected","collectionURL":"https://access.redhat.com/downloads/content/package-browser/","cpes":["cpe:/o:redhat:enterprise_linux:9"]}],"references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-70367","tags":["vdb-entry","x_refsource_REDHAT"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2462083","name":"RHBZ#2462083","tags":["issue-tracking","x_refsource_REDHAT"]}],"metrics":[{"other":{"content":{"value":"Moderate","namespace":"https://access.redhat.com/security/updates/classification/"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.4,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","description":"Server-Side Request Forgery (SSRF)","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"redhat","orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateUpdated":"2026-08-06T07:28:08.760Z"},"datePublic":"2026-08-04T10:29:57.207Z","x_redhatCweChain":"CWE-918: Server-Side Request Forgery (SSRF)","workarounds":[{"lang":"en","value":"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."}],"timeline":[{"lang":"en","time":"2026-04-26T18:12:08.000Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-08-04T10:29:57.207Z","value":"Made public."}],"credits":[{"lang":"en","value":"This issue was discovered by Found by AISLE in partnership with Red Hat."}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2462083","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-04T14:50:26.922087Z","id":"CVE-2026-70367","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-04T14:50:38.160Z"}}]}}}