What’s Vulnerable › Vulnerabilities

CVE-2022-29245: Weak private key generation in SSH.NET

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-05-31 · updated 2026-06-17
• Weakness: CWE-338

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.

Affected products

• sshnet SSH.NET: 2020.0.0, 2020.0.0-beta1, 2020.0.1

References

• https://github.com/sshnet/SSH.NET/blob/bc99ada7da3f05f50d9379f2644941d91d5bf05a/src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs#L51
• https://github.com/sshnet/SSH.NET/commit/03c6d60736b8f7b42e44d6989a53f9b644a091fb
• https://github.com/sshnet/SSH.NET/releases/tag/2020.0.2
• https://github.com/sshnet/SSH.NET/security/advisories/GHSA-72p8-v4hg-v45p
• https://github.com/sshnet/SSH.NET/blob/bc99ada7da3f05f50d9379f2644941d91d5bf05a/src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs#L51
• https://github.com/sshnet/SSH.NET/commit/03c6d60736b8f7b42e44d6989a53f9b644a091fb
• https://github.com/sshnet/SSH.NET/releases/tag/2020.0.2
• https://github.com/sshnet/SSH.NET/security/advisories/GHSA-72p8-v4hg-v45p

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