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Fencer Vulns
medium 5.9

CVE-2016-6329 json

OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a lo…

published 2017-01-31 9 y ago modified 2026-06-17 4 mo ago also EUVD-2016-7256

cvss
5.9
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
5.9%
EPSS 5.9% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

Summary

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.

Patch / fix

  • openvpn Ubuntu 14.04 LTS 2.3.2-7ubuntu3.2
  • openvpn Ubuntu 16.04 LTS 2.3.10-1ubuntu2.1

ubuntu advisories UBUNTU-CVE-2016-6329

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openvpn SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +2 more 2.0.9-143.47.3.1
  • openvpn SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2, SLES 12 SP2 +1 more 2.3.8-16.14.1

suse advisories SUSE-SU-2017:2838-1SUSE-SU-2017:1622-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-6329 updated cvss 3.7

openvpn: Birthday attack against BF-CBC used by default (SWEET32)

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-19-192-04 updated cvss 5.9

ICSA-19-192-04 Siemens SIMATIC RF6XXR

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

5.94% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-310 Cryptographic Issues

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.