{"id":"CVE-2026-47269","state":"PUBLISHED","title":"pam_usb: deny_remote feature incorrectly classifies IPv4-mapped IPv6 remote connections as local","description":"pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0,  pam_usb's deny_remote feature checks utmpx ut_addr_v6 to detect whether an authentication request originates from a remote session. The outer guard was if (utent->ut_addr_v6[0] != 0), which only tests the first 32-bit word of the 128-bit address field. IPv4-mapped IPv6 addresses (::ffff:x.x.x.x) store the IPv4 address in ut_addr_v6[3] with ut_addr_v6[0] == 0. On systems where the SSH daemon listens on :: (IPv6 wildcard) with AddressFamily any -- common on Ubuntu and Debian -- incoming IPv4 connections are recorded in utmpx as IPv4-mapped IPv6 addresses. The outer check evaluates to false, the remote-detection block is skipped entirely, and the session is treated as local. deny_remote=true does not block the authentication. An attacker with physical access to a registered USB device can authenticate over SSH on an affected system as if they were sitting at a local terminal, bypassing the deny_remote restriction. This vulnerability is fixed in 0.9.0.","publishedAt":"2026-05-27T20:11:44.975Z","updatedAt":"2026-05-28T12:50:50.859Z","severity":{"score":7.4,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["mcdope pam_usb"],"affected":[{"vendor":"mcdope","product":"pam_usb","versions":[{"version":"< 0.9.0","status":"affected"}]}],"references":["https://github.com/mcdope/pam_usb/security/advisories/GHSA-jmmj-qhrq-w45g","https://github.com/mcdope/pam_usb/commit/804fe24eae3d742d8be05fd015e36abc3c7d94e5"],"weaknesses":["CWE-284"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/47xxx/CVE-2026-47269.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-47269","state":"PUBLISHED","datePublished":"2026-05-27T20:11:44.975Z","dateUpdated":"2026-05-28T12:50:50.859Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-05-18T23:03:37.229Z"},"containers":{"cna":{"title":"pam_usb: deny_remote feature incorrectly classifies IPv4-mapped IPv6 remote connections as local","descriptions":[{"lang":"en","value":"pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.0,  pam_usb's deny_remote feature checks utmpx ut_addr_v6 to detect whether an authentication request originates from a remote session. The outer guard was if (utent->ut_addr_v6[0] != 0), which only tests the first 32-bit word of the 128-bit address field. IPv4-mapped IPv6 addresses (::ffff:x.x.x.x) store the IPv4 address in ut_addr_v6[3] with ut_addr_v6[0] == 0. On systems where the SSH daemon listens on :: (IPv6 wildcard) with AddressFamily any -- common on Ubuntu and Debian -- incoming IPv4 connections are recorded in utmpx as IPv4-mapped IPv6 addresses. The outer check evaluates to false, the remote-detection block is skipped entirely, and the session is treated as local. deny_remote=true does not block the authentication. An attacker with physical access to a registered USB device can authenticate over SSH on an affected system as if they were sitting at a local terminal, bypassing the deny_remote restriction. This vulnerability is fixed in 0.9.0."}],"affected":[{"vendor":"mcdope","product":"pam_usb","versions":[{"version":"< 0.9.0","status":"affected"}]}],"references":[{"url":"https://github.com/mcdope/pam_usb/security/advisories/GHSA-jmmj-qhrq-w45g","name":"https://github.com/mcdope/pam_usb/security/advisories/GHSA-jmmj-qhrq-w45g","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/mcdope/pam_usb/commit/804fe24eae3d742d8be05fd015e36abc3c7d94e5","name":"https://github.com/mcdope/pam_usb/commit/804fe24eae3d742d8be05fd015e36abc3c7d94e5","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-284","lang":"en","description":"CWE-284: Improper Access Control","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-27T20:11:44.975Z"},"source":{"advisory":"GHSA-jmmj-qhrq-w45g","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-28T12:50:16.970323Z","id":"CVE-2026-47269","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-28T12:50:50.859Z"}}]}}}