CVE-2022-29245
Weak private key generation in SSH.NET
- State
- Published
- Severity
- 6.5 Medium
- Published
- May 31, 2022
- Updated
- Apr 22, 2025
- Reserved
- Apr 13, 2022
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.5 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N | GitHub_M |
Weaknesses
- CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
Affected Products
| Product | Versions |
|---|---|
SSH.NETsshnet |
|
References
- https://github.com/sshnet/SSH.NET/security/advisories/GHSA-72p8-v4hg-v45p
- https://github.com/sshnet/SSH.NET/commit/03c6d60736b8f7b42e44d6989a53f9b644a091fb
- https://github.com/sshnet/SSH.NET/blob/bc99ada7da3f05f50d9379f2644941d91d5bf05a/src/Renci.SshNet/Security/KeyExchangeECCurve25519.cs#L51
- https://github.com/sshnet/SSH.NET/releases/tag/2020.0.2
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