{"id":"CVE-2016-6329","aliases":["DEBIAN-CVE-2016-6329","EUVD-2016-7256","GHSA-w6pr-cm6j-f384","MGASA-2016-0304","SUSE-SU-2017:1622-1","SUSE-SU-2017:2838-1","UBUNTU-CVE-2016-6329","USN-3339-1"],"status":"published","title":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain...","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","severity":{"version":"3.0","score":5.9,"vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-08","score":0.0594,"percentile":0.93315,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-200","CWE-310"],"published":"2016-09-16T09:27:13Z","modified":"2026-10-24T10:30:29Z","fixes":[{"ecosystem":"Mageia:5","package":"openvpn","fixed_in":["2.3.12-1.mga5"],"sources":["osv"]},{"ecosystem":"Ubuntu:14.04:LTS","package":"openvpn","fixed_in":["2.3.2-7ubuntu3.2"],"sources":["osv"]},{"ecosystem":"Ubuntu:16.04:LTS","package":"openvpn","fixed_in":["2.3.10-1ubuntu2.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Mageia:5","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.12-1.mga5"}]}]},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Desktop 12 SP2","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.8-16.14.1"}]}],"bundled":3},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for Raspberry Pi 12 SP2","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.8-16.14.1"}]}],"bundled":3},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 12 SP2","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.8-16.14.1"}]}],"bundled":3},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 12 SP2","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.8-16.14.1"}]}],"bundled":3},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Point of Sale 11 SP3","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.9-143.47.3.1"}]}],"bundled":4},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 11 SP3-LTSS","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.9-143.47.3.1"}]}],"bundled":4},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 11 SP3-TERADATA","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.9-143.47.3.1"}]}],"bundled":4},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 11 SP4","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.9-143.47.3.1"}]}],"bundled":4},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 11 SP4","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.9-143.47.3.1"}]}],"bundled":4},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.2-7ubuntu3.2"}]}],"versions":["2.3.2-4ubuntu1","2.3.2-5ubuntu1","2.3.2-7ubuntu1","2.3.2-7ubuntu2","2.3.2-7ubuntu3","2.3.2-7ubuntu3.1"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.10-1ubuntu2.1"}]}],"versions":["2.3.7-1ubuntu1","2.3.7-2ubuntu1","2.3.8-1ubuntu1","2.3.10-1ubuntu1","2.3.10-1ubuntu2"]},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.2-7ubuntu3.2"}]}],"versions":["2.3.2-4ubuntu1","2.3.2-5ubuntu1","2.3.2-7ubuntu1","2.3.2-7ubuntu2","2.3.2-7ubuntu3","2.3.2-7ubuntu3.1"],"bundled":5},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"openvpn","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.3.10-1ubuntu2.1"}]}],"versions":["2.3.7-1ubuntu1","2.3.7-2ubuntu1","2.3.8-1ubuntu1","2.3.10-1ubuntu1","2.3.10-1ubuntu2"],"bundled":5}],"products":[{"vendor":"openvpn","product":"openvpn"}],"references":[{"url":"https://sweet32.info/","tags":["x_refsource_MISC","x_transferred","Technical Description","Third Party Advisory","advisory","report"]},{"url":"https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05369403","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory"]},{"url":"http://www.securitytracker.com/id/1036695","tags":["vdb-entry","x_refsource_SECTRACK","x_transferred","Third Party Advisory","VDB Entry","advisory"]},{"url":"http://www-01.ibm.com/support/docview.wss?uid=swg21995039","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory"]},{"url":"http://www-01.ibm.com/support/docview.wss?uid=swg21991482","tags":["x_refsource_CONFIRM","x_transferred","Third Party Advisory","advisory"]},{"url":"https://security.gentoo.org/glsa/201611-02","tags":["vendor-advisory","x_refsource_GENTOO","x_transferred","Third Party Advisory","advisory"]},{"url":"https://community.openvpn.net/openvpn/wiki/SWEET32","tags":["x_refsource_CONFIRM","x_transferred","Vendor Advisory","advisory","report"]},{"url":"http://www-01.ibm.com/support/docview.wss?uid=nas8N1021697","tags":["x_refsource_CONFIRM","x_transferred","Permissions Required","Third Party Advisory","report"]},{"url":"http://www.securityfocus.com/bid/92631","tags":["vdb-entry","x_refsource_BID","x_transferred","Third Party Advisory","VDB Entry","advisory"]},{"url":"https://cert-portal.siemens.com/productcert/pdf/ssa-556833.pdf","tags":["x_refsource_CONFIRM","x_transferred","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2016-6329"},{"url":"https://sweet32.info"},{"url":"https://github.com/advisories/GHSA-w6pr-cm6j-f384"},{"url":"https://security-tracker.debian.org/tracker/CVE-2016-6329","tags":["advisory"]},{"url":"https://advisories.mageia.org/MGASA-2016-0304.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=19251","tags":["report"]},{"url":"https://community.openvpn.net/openvpn/wiki/ChangesInOpenvpn23","tags":["web"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/thread/IIPSFOGSRZ5PCY7HRYCDJADE4DTIBMML/","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2017/suse-su-20171622-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1038709","tags":["report"]},{"url":"https://bugzilla.suse.com/1038711","tags":["report"]},{"url":"https://bugzilla.suse.com/1038713","tags":["report"]},{"url":"https://bugzilla.suse.com/995374","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2016-6329","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2017-7478","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2017-7479","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2017/suse-su-20172838-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1060877","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2017-12166","tags":["web"]},{"url":"https://ubuntu.com/security/CVE-2016-6329","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-3339-1","tags":["advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2016-6329","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2017-7479","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2017-7508","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2017-7520","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2017-7521","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2016-6329","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"published","published":"2017-01-31T22:00:00Z","modified":"2024-08-06T01:29:18.449Z","updated_at":"2026-11-02T14:33:34.443637Z"}],"euvd":[{"id":"EUVD-2016-7256","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"published","published":"2017-01-31T22:00:00Z","modified":"2024-08-06T01:29:18Z","updated_at":"2026-11-03T02:22:39.91691Z"}],"ghsa":[{"id":"GHSA-w6pr-cm6j-f384","title":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain...","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"published","published":"2022-05-14T00:56:55Z","modified":"2025-04-20T03:33:08Z","cvss":[{"version":"3.0","score":5.9,"vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"cwes":["CWE-200"],"updated_at":"2026-11-02T15:01:40.176288Z"}],"nvd":[{"id":"CVE-2016-6329","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"published","published":"2017-01-31T22:59:00.377Z","modified":"2026-06-17T00:50:50.307Z","cvss":[{"version":"3.0","score":5.9,"vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"primary"},{"version":"2.0","score":4.3,"vector":"AV:N/AC:M/Au:N/C:P/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-200","CWE-310"],"updated_at":"2026-11-02T14:03:35.029632Z"}],"osv":[{"id":"CVE-2016-6329","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"published","published":"2017-01-31T22:59:00.377Z","modified":"2026-10-24T10:30:29.969449713Z","cvss":[{"version":"3.0","score":5.9,"vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:44:02.776224Z"},{"id":"DEBIAN-CVE-2016-6329","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"withdrawn","published":"2017-01-31T22:59:00.377Z","modified":"2025-12-08T01:49:35.8216Z","cvss":[{"version":"3.0","score":5.9,"vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:27.910042Z"},{"id":"UBUNTU-CVE-2016-6329","description":"OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a long-duration encrypted session, as demonstrated by an HTTP-over-OpenVPN session using Blowfish in CBC mode, aka a \"Sweet32\" attack.","status":"published","published":"2017-01-31T00:00:00Z","modified":"2026-02-04T04:16:52.30652Z","cvss":[{"version":"3.0","score":5.9,"vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T15:54:12.642042Z"},{"id":"MGASA-2016-0304","title":"Updated openvpn packages fix security vulnerability","description":"Ciphers with 64-bit block sizes used in CBC mode were found to be\nvulnerable to birthday attack when key renegotiation doesn't happen\nfrequently or at all in long running connections. Blowfish cipher as used\nin OpenVPN by default is vulnerable to this attack, that allows remote\nattacker to recover partial plaintext information (XOR of two plaintext\nblocks) (CVE-2016-6329).\n","status":"published","published":"2016-09-16T09:27:13Z","modified":"2026-04-16T06:22:55.168334569Z","updated_at":"2026-11-02T15:49:40.103088Z"},{"id":"SUSE-SU-2017:1622-1","title":"Security update for openvpn","description":"This update for openvpn fixes the following issues:\n\n- CVE-2016-6329: Show which ciphers should no longer be used in openvpn --show-ciphers (bsc#995374)\n- CVE-2017-7478: openvpn: Authenticated user can DoS server by using a big payload in P_CONTROL (bsc#1038709)\n- CVE-2017-7479: openvpn: Denial of Service due to Exhaustion of Packet-ID counter (bsc#1038711)\n- Hardening measures found by internal audit (bsc#1038713)\n\n\n","status":"published","published":"2017-06-20T06:39:38Z","modified":"2026-02-04T02:28:42.945154Z","updated_at":"2026-11-02T15:53:43.83457Z"},{"id":"SUSE-SU-2017:2838-1","title":"Security update for openvpn","description":"\n\nThis update for openvpn fixes the following security issues:\n\n- CVE-2017-12166: OpenVPN was vulnerable to a buffer overflow vulnerability when key-method 1 is used, possibly resulting in code execution. (bsc#1060877).\n- CVE-2016-6329: Now show which ciphers should no longer be used in openvpn --show-ciphers to avoid the SWEET32 attack (bsc#995374)\n- CVE-2017-7478: OpenVPN was vulnerable to unauthenticated Denial of Service of server via received large control packet. (bsc#1038709)\n- CVE-2017-7479: OpenVPN was vulnerable to reachable assertion when packet-ID counter rolls over resulting into Denial of Service of server by authenticated attacker. (bsc#1038711)\n- Some other hardening fixes have also been applied (bsc#1038713)\n","status":"published","published":"2017-10-24T09:59:40Z","modified":"2026-02-04T03:53:27.509319Z","updated_at":"2026-11-02T15:53:44.209561Z"},{"id":"USN-3339-1","title":"openvpn vulnerabilities","description":"Karthikeyan Bhargavan and Gaëtan Leurent discovered that 64-bit block\nciphers are vulnerable to a birthday attack. A remote attacker could\npossibly use this issue to recover cleartext data. Fixing this issue\nrequires a configuration change to switch to a different cipher. This\nupdate adds a warning to the log file when a 64-bit block cipher is in use.\nThis issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and\nUbuntu 16.10. (CVE-2016-6329)\n\nIt was discovered that OpenVPN incorrectly handled rollover of packet ids.\nAn authenticated remote attacker could use this issue to cause OpenVPN to\ncrash, resulting in a denial of service. This issue only affected Ubuntu\n14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2017-7479)\n\nGuido Vranken discovered that OpenVPN incorrectly handled certain malformed\nIPv6 packets. A remote attacker could use this issue to cause OpenVPN to\ncrash, resulting in a denial of service. (CVE-2017-7508)\n\nGuido Vranken discovered that OpenVPN incorrectly handled an HTTP proxy\nwith NTLM authentication. A remote attacker could use this issue to cause\nOpenVPN clients to crash, resulting in a denial of service, or possibly\nexpose sensitive memory contents. (CVE-2017-7520)\n\nGuido Vranken discovered that OpenVPN incorrectly handled certain x509\nextensions. A remote attacker could use this issue to cause OpenVPN to\ncrash, resulting in a denial of service. (CVE-2017-7521)\n\n","status":"published","published":"2017-06-22T18:02:03Z","modified":"2026-02-10T04:41:09Z","updated_at":"2026-11-02T16:58:13.496563Z"}]}}