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.
http://www.securityfocus.com/bid/92631
http://www.securitytracker.com/id/1036695
http://www-01.ibm.com/support/docview.wss?uid=nas8N1021697
http://www-01.ibm.com/support/docview.wss?uid=swg21991482
http://www-01.ibm.com/support/docview.wss?uid=swg21995039
https://cert-portal.siemens.com/productcert/pdf/ssa-556833.pdf
https://community.openvpn.net/openvpn/wiki/SWEET32
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05369403
Source: MITRE
Published: 2017-01-31
Updated: 2019-07-09
Type: CWE-200
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.9
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Impact Score: 3.6
Exploitability Score: 2.2
Severity: MEDIUM