CVE-2022-29245 is a medium-severity (CVSS 6.5) CWE-338 vulnerability in SSH.NET. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for SSH.NET — see the affected versions and patch details below.
Weak private key generation in SSH.NET
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2022-29245.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
SSH.NETReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
During an X25519 key exchange, the client’s private is generated with System.Random:
var rnd = new Random();
_privateKey = new byte[MontgomeryCurve25519.PrivateKeySizeInBytes];
rnd.NextBytes(_privateKey);
Source: KeyExchangeECCurve25519.cs
Source commit: https://github.com/sshnet/SSH.NET/commit/b58a11c0da55da1f5bad46faad2e9b71b7cb35b3
System.Random is not a cryptographically secure random number generator, it must therefore not be used for cryptographic purposes.
Impact
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 bruteforced. This allows an attacker able to eavesdrop the communications to decrypt them.
Workarounds
To ensure you're not affected by this vulnerability, you can disable support for curve25519-sha256 and [email protected] key exchange algorithms by invoking the following method before a connection is established:
private static void RemoveUnsecureKEX(BaseClient client)
{
client.ConnectionInfo.KeyExchangeAlgorithms.Remove("curve25519-sha256");
client.ConnectionInfo.KeyExchangeAlgorithms.Remove("[email protected]");
}
Thanks
This issue was initially reported by Siemens AG, Digital Industries, shortly followed by @yaumn-synacktiv.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | SSH.NET | all versions | 2020.0.2dotnet add package SSH.NET --version 2020.0.2 |
Affected Products
ssh.netssh.net_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for SSH.NET, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update SSH.NET to 2020.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-29245 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2022-29245 in your dependencies?
Find it across NuGet, including transitive dependencies.