{"id":"CVE-2026-48737","state":"PUBLISHED","title":"pyLoad: SSRF guard bypass via IPv6 6to4/NAT64 transition wrappers of internal IPs","description":"pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev101, is_global_address in src/pyload/core/utils/web/check.py relies on Python's global-address classification without examining IPv4 destinations embedded in 6to4 or NAT64 IPv6 addresses. A low-privileged user can submit an IPv6 literal through parse_urls to the pre-resolution is_global_host guard. Because host_to_ip is pinned to AF_INET, that guard does not evaluate a hostname's AAAA result. Separately, curl resolves hostnames before the pycurl PREREQFUNC in src/pyload/core/network/http/http_request.py applies the same vulnerable is_global_address check to the actual connection address, so a transition-form AAAA result can be permitted even when it terminates at an embedded loopback, private, CGNAT, or link-local IPv4 address. Exploitation requires the pyLoad host to route the applicable transition mechanism, including 6to4 on affected Python 3.9 through 3.11 deployments or NAT64 on a network with a NAT64 gateway. Successful exploitation can enable internal-network reconnaissance, timing-based confirmation, limited service disruption, or cloud metadata disclosure where the wrapped address is routable. This issue is fixed in version 0.5.0b3.dev101.","publishedAt":"2026-09-15T14:40:27.340Z","updatedAt":"2026-09-16T16:04:53.088Z","severity":{"score":4.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["pyload pyload"],"affected":[{"vendor":"pyload","product":"pyload","versions":[{"version":"< 0.5.0b3.dev101","status":"affected"}]}],"references":["https://github.com/pyload/pyload/security/advisories/GHSA-m5x5-28jr-gpjj","https://github.com/pyload/pyload/commit/ba7491046b2d430732be490913e4cbf1f1e899c2"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/48xxx/CVE-2026-48737.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-48737","state":"PUBLISHED","datePublished":"2026-09-15T14:40:27.340Z","dateUpdated":"2026-09-16T16:04:53.088Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-22T19:10:35.746Z"},"containers":{"cna":{"title":"pyLoad: SSRF guard bypass via IPv6 6to4/NAT64 transition wrappers of internal IPs","descriptions":[{"lang":"en","value":"pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev101, is_global_address in src/pyload/core/utils/web/check.py relies on Python's global-address classification without examining IPv4 destinations embedded in 6to4 or NAT64 IPv6 addresses. A low-privileged user can submit an IPv6 literal through parse_urls to the pre-resolution is_global_host guard. Because host_to_ip is pinned to AF_INET, that guard does not evaluate a hostname's AAAA result. Separately, curl resolves hostnames before the pycurl PREREQFUNC in src/pyload/core/network/http/http_request.py applies the same vulnerable is_global_address check to the actual connection address, so a transition-form AAAA result can be permitted even when it terminates at an embedded loopback, private, CGNAT, or link-local IPv4 address. Exploitation requires the pyLoad host to route the applicable transition mechanism, including 6to4 on affected Python 3.9 through 3.11 deployments or NAT64 on a network with a NAT64 gateway. Successful exploitation can enable internal-network reconnaissance, timing-based confirmation, limited service disruption, or cloud metadata disclosure where the wrapped address is routable. This issue is fixed in version 0.5.0b3.dev101."}],"affected":[{"vendor":"pyload","product":"pyload","versions":[{"version":"< 0.5.0b3.dev101","status":"affected"}]}],"references":[{"url":"https://github.com/pyload/pyload/security/advisories/GHSA-m5x5-28jr-gpjj","name":"https://github.com/pyload/pyload/security/advisories/GHSA-m5x5-28jr-gpjj","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/pyload/pyload/commit/ba7491046b2d430732be490913e4cbf1f1e899c2","name":"https://github.com/pyload/pyload/commit/ba7491046b2d430732be490913e4cbf1f1e899c2","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.9,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-15T14:40:27.340Z"},"source":{"advisory":"GHSA-m5x5-28jr-gpjj","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/pyload/pyload/security/advisories/GHSA-m5x5-28jr-gpjj","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-16T16:04:41.559990Z","id":"CVE-2026-48737","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":"2026-09-16T16:04:53.088Z"}}]}}}