CVE-2025-52570

Description

Letmein is an authenticating port knocker. Prior to version 10.2.1, The connection limiter is implemented incorrectly. It allows an arbitrary amount of simultaneously incoming connections (TCP, UDP and Unix socket) for the services letmeind and letmeinfwd. Therefore, the command line option num-connections is not effective and does not limit the number of simultaneously incoming connections. This issue has been patched in version 10.2.1.

Weakness Type (CWE)

CWE-770 CWE-770

CWE-799 CWE-799

References

Other References

https://github.com/mbuesch/letmein/commit/43207cd77580410d97165d1e3c07361ba6f3558c https://github.com/mbuesch/letmein/security/advisories/GHSA-jpv7-p47h-f43j

Frequently Asked Questions

What is CVE-2025-52570? +

Letmein is an authenticating port knocker. Prior to version 10.2.1, The connection limiter is implemented incorrectly. It allows an arbitrary amount of simultaneously incoming connections (TCP, UDP and Unix socket) for the services letmeind and letmeinfwd. Therefore, the command line option num-connections is not effective and does not limit the number of simultaneously incoming connections. This issue has been patched in version 10.2.1.

How do I check if I'm vulnerable to CVE-2025-52570? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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