CVE-2025-52570: Letmeind Letmein Connection Limiter Allows An Vulnerability

MODERATE
Advisory Identifier: GHSA-jpv7-p47h-f43j
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CWE-770
Published
Advisory Summary

CVE-2025-52570 is a MODERATE letmein connection limiter allows an vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Letmeind libraries in the crates.io ecosystem. The issue involves letmein connection limiter allows an arbitrary amount of simultaneous connections. Remediation is available by upgrading affected packages to version 10.2.1.

CVE-2025-52570 at a Glance

CVE Identifier CVE-2025-52570
GHSA Identifier GHSA-jpv7-p47h-f43j
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Letmeind
Package Ecosystem crates.io
Published Date
Last Updated

How to Fix CVE-2025-52570

To remediate this vulnerability, upgrade all affected Letmeind dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

letmeind fixed: 10.2.1 
Upgrade letmeind to 10.2.1
letmeinfwd fixed: 10.2.1 
Upgrade letmeinfwd to 10.2.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for letmeind

How to Check if You Are Affected

To determine whether your application is affected by CVE-2025-52570, inspect your project dependencies for Letmeind:

inspect dependencies for letmeind

Analyze the terminal output to locate any version of Letmeind in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.2.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Letmeind, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact 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. `letmeind` is the public network facing daemon (TCP/UDP). `letmeinfwd` is the internal firewall daemon that only listens on local Unix socket. Possible Denial Of Service by resource exhaustion. ### Affected versions All versions `<= 10.2.0` are affected. ### Patches All users shall upgrade to version `10.2.1`. ### Workarounds Untested possible workarounds: - It might be possible to limit the number of active connections to the `letmeind` port (default 5800) via firewall. - The resource consumption of the service might be restricted with a service manager such as systemd. ### Severity: If a (D)DoS is run against the service, *something* is going to be affected. The connection limiter assures that the effect on the system itself is limited at the expense of the effect on the letmein services itself. So even with the connection limiter active, a (D)DoS can lead to a less responsive or unresponsive letmein service.

CVE-2025-52570 Affected Letmeind Versions

2 component(s)
Fixed Versions:
10.2.1
Product / Package Ecosystem Affected Versions Fixed Version
letmeind
 crates.io
< 10.2.1
10.2.1
letmeinfwd
 crates.io
< 10.2.1
10.2.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/mbuesch/letmein/security/advisories/GHSA-jpv7-p47h-f43j
NVD — CVE-2025-52570 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-52570
Security Fix Commit FIX COMMIT
https://github.com/mbuesch/letmein/commit/43207cd77580410d97165d1e3c07361ba6f3558c
Letmeind Source Repository REPOSITORY
https://github.com/mbuesch/letmein

Frequently Asked Questions

What is CVE-2025-52570?
CVE-2025-52570 is a security vulnerability in Letmeind involving letmein connection limiter allows an arbitrary amount of simultaneous connections under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Letmeind versions are affected?
Affected versions include releases prior to 10.2.1 across affected packages: letmeind, letmeinfwd.
What version fixes CVE-2025-52570?
Upgrading to 10.2.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is letmeind affected?
Yes, letmeind is affected in releases prior to 10.2.1. Upgrade your dependency to 10.2.1 or later.
Is letmeinfwd affected?
Yes, letmeinfwd is affected in releases prior to 10.2.1. Upgrade your dependency to 10.2.1 or later.
What CWE is associated with CVE-2025-52570?
CVE-2025-52570 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check crates.io dependencies for CVE-2025-52570?
Run the dependency tree command: 'inspect dependencies for letmeind'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jpv7-p47h-f43j",
  "modified" : "2025-06-27T23:08:47Z",
  "published" : "2025-06-23T21:24:59Z",
  "aliases" : [ "CVE-2025-52570" ],
  "summary" : "letmein connection limiter allows an arbitrary amount of simultaneous connections",
  "details" : "### Impact\n\nThe connection limiter is implemented incorrectly.\nIt allows an arbitrary amount of simultaneously incoming connections (TCP, UDP and Unix socket) for the services `letmeind` and `letmeinfwd`.\nTherefore, the command line option `num-connections` is not effective and does not limit the number of simultaneously incoming connections.\n\n`letmeind` is the public network facing daemon (TCP/UDP).\n\n`letmeinfwd` is the internal firewall daemon that only listens on local Unix socket.\n\nPossible Denial Of Service by resource exhaustion.\n\n### Affected versions\nAll versions `<= 10.2.0` are affected.\n\n### Patches\nAll users shall upgrade to version `10.2.1`.\n\n### Workarounds\n\nUntested possible workarounds:\n- It might be possible to limit the number of active connections to the `letmeind` port (default 5800) via firewall.\n- The resource consumption of the service might be restricted with a service manager such as systemd.\n\n### Severity:\n\nIf a (D)DoS is run against the service, *something* is going to be affected.\nThe connection limiter assures that the effect on the system itself is limited at the expense of the effect on the letmein services itself.\nSo even with the connection limiter active, a (D)DoS can lead to a less responsive or unresponsive letmein service.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "letmeind"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "10.2.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.2.0"
    }
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "letmeinfwd"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "10.2.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.2.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/mbuesch/letmein/security/advisories/GHSA-jpv7-p47h-f43j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-52570"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mbuesch/letmein/commit/43207cd77580410d97165d1e3c07361ba6f3558c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mbuesch/letmein"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-06-23T21:24:59Z",
    "nvd_published_at" : "2025-06-24T04:15:50Z"
  }
}