Description
SSH.NET is a Secure Shell (SSH) library for .NET. In versions 2020.0.0 and 2020.0.1, during an `X25519` key exchange, the client’s private key is generated with `System.Random`. `System.Random` is not a cryptographically secure random number generator, it must therefore not be used for cryptographic purposes. When establishing an SSH connection to a remote host, during the X25519 key exchange, the private key is generated with a weak random number generator whose seed can be brute forced. This allows an attacker who is able to eavesdrop on the communications to decrypt them. Version 2020.0.2 contains a patch for this issue. As a workaround, one may disable support for `curve25519-sha256` and `curve25519-sha256@libssh.org` key exchange algorithms.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:NWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| sshnet | SSH.NET | >= 2020.0.0, < 2020.0.2 |
References
- https://github.com/sshnet/SSH.NET/blob/bc99ada7da3f05f50d9379f2644941d91d5bf05a/src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs#L51Exploit, Third Party Advisory
- https://github.com/sshnet/SSH.NET/commit/03c6d60736b8f7b42e44d6989a53f9b644a091fbPatch, Third Party Advisory
- https://github.com/sshnet/SSH.NET/releases/tag/2020.0.2Release Notes, Third Party Advisory
- https://github.com/sshnet/SSH.NET/security/advisories/GHSA-72p8-v4hg-v45pExploit, Mitigation, Third Party Advisory
- https://github.com/sshnet/SSH.NET/blob/bc99ada7da3f05f50d9379f2644941d91d5bf05a/src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs#L51Exploit, Third Party Advisory
- https://github.com/sshnet/SSH.NET/commit/03c6d60736b8f7b42e44d6989a53f9b644a091fbPatch, Third Party Advisory
- https://github.com/sshnet/SSH.NET/releases/tag/2020.0.2Release Notes, Third Party Advisory
- https://github.com/sshnet/SSH.NET/security/advisories/GHSA-72p8-v4hg-v45pExploit, Mitigation, Third Party Advisory
Timeline
- Published
- May 31, 2022
- Last modified
- Jun 17, 2026
- NVD status
- Modified