Vulnerability · Published Jun 24, 2025 · Assigned by GitHub_M

CVE-2025-52570Letmein connection limiter allows an arbitrary amount of simultaneous connections

Low 1.7

In plain English

A low-severity resource allocation without limits in letmein from mbuesch. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities).

Severity (CVSS 4.0)1.7Low

Exploit odds (30 days)0.4%top 68.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
mbuesch	letmein	< 10.2.1

Weakness: CWE-799, CWE-770 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U

References

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