Low
Letmein connection limiter allows an arbitrary amount of simultaneous connections
Type: advisorySources: OSV
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2025-52570
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 2 Nov 2026, 21:00 UTC · Revision 1
Source evidence
Letmein connection limiter allows an arbitrary amount of simultaneous connections
core-osv · Original sourcePublished 24 Jun 2025, 03:13 UTC
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.
osv:CVE-2025-52570
Complete source record
{
"id": "4e9caf243181af8747df08b48ac02b20159bc61896e12c862a57769a5c594e80",
"url": "https://osv.dev/vulnerability/CVE-2025-52570",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Letmein connection limiter allows an arbitrary amount of simultaneous connections",
"summary": "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.",
"evidence": "osv:CVE-2025-52570",
"products": [],
"severity": "low",
"structured": {
"id": "CVE-2025-52570",
"aliases": [
"CVE-2025-52570",
"GHSA-jpv7-p47h-f43j"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "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"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/mbuesch/letmein",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "043bd3db7d3cfd4da88ca47a3f757f9d22c3d164"
},
{
"fixed": "43207cd77580410d97165d1e3c07361ba6f3558c"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "10.2.1"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "43207cd77580410d97165d1e3c07361ba6f3558c"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"letmeinfwd-10.2.0",
"letmeind-10.2.0",
"letmein-systemd-10.2.0",
"letmein-seccomp-10.2.0",
"letmein-proto-10.2.0",
"letmein-fwproto-10.2.0",
"letmein-conf-10.2.0",
"letmein-10.2.0",
"letmeinfwd-10.1.0",
"letmeind-10.1.0",
"letmein-systemd-10.1.0",
"letmein-seccomp-10.1.0",
"letmein-proto-10.1.0",
"letmein-fwproto-10.1.0",
"letmein-conf-10.1.0",
"letmein-10.1.0",
"letmeinfwd-10.0.1",
"letmeind-10.0.1",
"letmein-systemd-10.0.1",
"letmein-seccomp-10.0.1",
"letmein-proto-10.0.1",
"letmein-fwproto-10.0.1",
"letmein-conf-10.0.1",
"letmein-10.0.1",
"letmeinfwd-10.0.0",
"letmeind-10.0.0",
"letmein-systemd-10.0.0",
"letmein-seccomp-10.0.0",
"letmein-proto-10.0.0",
"letmein-fwproto-10.0.0",
"letmein-conf-10.0.0",
"letmein-10.0.0",
"letmeinfwd-9.0.0",
"letmeind-9.0.0",
"letmein-systemd-9.0.0",
"letmein-seccomp-9.0.0",
"letmein-proto-9.0.0",
"letmein-fwproto-9.0.0",
"letmein-conf-9.0.0",
"letmein-9.0.0",
"letmeinfwd-8.0.0",
"letmeind-8.0.0",
"letmein-systemd-8.0.0",
"letmein-seccomp-8.0.0",
"letmein-proto-8.0.0",
"letmein-fwproto-8.0.0",
"letmein-conf-8.0.0",
"letmein-8.0.0",
"letmeinfwd-7.2.0",
"letmeind-7.2.0",
"letmein-systemd-7.2.0",
"letmein-seccomp-7.2.0",
"letmein-proto-7.2.0",
"letmein-fwproto-7.2.0",
"letmein-conf-7.2.0",
"letmein-7.2.0",
"letmeinfwd-7.1.0",
"letmeind-7.1.0",
"letmein-systemd-7.1.0",
"letmein-seccomp-7.1.0",
"letmein-proto-7.1.0",
"letmein-fwproto-7.1.0",
"letmein-conf-7.1.0",
"letmein-7.1.0",
"letmeinfwd-7.0.0",
"letmeind-7.0.0",
"letmein-systemd-7.0.0",
"letmein-seccomp-7.0.0",
"letmein-proto-7.0.0",
"letmein-fwproto-7.0.0",
"letmein-conf-7.0.0",
"letmein-7.0.0",
"letmeinfwd-6.0.0",
"letmeind-6.0.0",
"letmein-systemd-6.0.0",
"letmein-seccomp-6.0.0",
"letmein-proto-6.0.0",
"letmein-fwproto-6.0.0",
"letmein-conf-6.0.0",
"letmein-6.0.0",
"letmeinfwd-5.1.0",
"letmeind-5.1.0",
"letmein-systemd-5.1.0",
"letmein-seccomp-5.1.0",
"letmein-proto-5.1.0",
"letmein-fwproto-5.1.0",
"letmein-conf-5.1.0",
"letmein-5.1.0",
"letmeinfwd-5.0.0",
"letmeind-5.0.0",
"letmein-systemd-5.0.0",
"letmein-seccomp-5.0.0",
"letmein-proto-5.0.0",
"letmein-fwproto-5.0.0",
"letmein-conf-5.0.0",
"letmein-5.0.0",
"letmeinfwd-4.0.0",
"letmeind-4.0.0",
"letmein-systemd-4.0.0",
"letmein-seccomp-4.0.0",
"letmein-proto-4.0.0",
"letmein-fwproto-4.0.0",
"letmein-conf-4.0.0",
"letmein-4.0.0",
"letmeinfwd-3.0.0",
"letmeind-3.0.0",
"letmein-systemd-3.0.0",
"letmein-seccomp-3.0.0",
"letmein-proto-3.0.0",
"letmein-fwproto-3.0.0",
"letmein-conf-3.0.0",
"letmein-3.0.0",
"letmeind-2.0.0",
"letmein-systemd-2.0.0",
"letmein-proto-2.0.0",
"letmein-conf-2.0.0",
"letmein-2.0.0",
"letmeind-1.1.0",
"letmein-systemd-1.1.0",
"letmein-proto-1.1.0",
"letmein-conf-1.1.0",
"letmein-1.1.0",
"letmeind-1.0.0",
"letmein-systemd-1.0.0",
"letmein-proto-1.0.0",
"letmein-conf-1.0.0",
"letmein-1.0.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-52570.json"
}
}
],
"modified": "2026-10-28T02:30:23.677498022Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/52xxx/CVE-2025-52570.json",
"https://github.com/mbuesch/letmein/security/advisories/GHSA-jpv7-p47h-f43j",
"https://nvd.nist.gov/vuln/detail/CVE-2025-52570",
"https://github.com/mbuesch/letmein/commit/43207cd77580410d97165d1e3c07361ba6f3558c"
],
"provider_metadata": {
"cwe_ids": [
"CWE-770",
"CWE-799"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/52xxx/CVE-2025-52570.json"
}
},
"related_cves": [
{
"value": "CVE-2025-52570",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 490040,
"published_at": "2025-06-24T03:13:29.37+00:00"
}