CVE-2018-7749: AsyncSSH Authentication Bypass Vulnerability

CRITICAL
Advisory Identifier: GHSA-97cv-6pjf-5f9q
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CVSS 9.8
CWE-287
Published
Advisory Summary

CVE-2018-7749 is a CRITICAL (CVSS 9.8) authentication bypass vulnerability (CWE-287: Improper Authentication) affecting AsyncSSH libraries in the PyPI ecosystem. The issue involves asyncssh ssh server authentication bypass. Remediation is available by upgrading affected packages to version 1.12.1.

CVE-2018-7749 at a Glance

CVE Identifier CVE-2018-7749
GHSA Identifier GHSA-97cv-6pjf-5f9q
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-287: Improper Authentication
Affected Product AsyncSSH
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2018-7749

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

AsyncSSH fixed: 1.12.1 
pip install AsyncSSH>=1.12.1
Verify Direct and Transitive Dependencies

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

pip show AsyncSSH

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2018-7749, inspect your installed packages using pip:

pip show AsyncSSH

Analyze the terminal output to locate any version of AsyncSSH in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.12.1), your application is affected.

Note: The pip show AsyncSSH command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In AsyncSSH, 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

The SSH server implementation of AsyncSSH before 1.12.1 does not properly check whether authentication is completed before processing other requests. A customized SSH client can simply skip the authentication step.

CVE-2018-7749 Affected AsyncSSH Versions

1 component(s)
Fixed Versions:
1.12.1
Product / Package Ecosystem Affected Versions Fixed Version
AsyncSSH
pypi/AsyncSSH
PyPI
< 1.12.1
1.12.1

References

NVD — CVE-2018-7749 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-7749
Security Fix Commit FIX COMMIT
https://github.com/ronf/asyncssh/commit/16e6ebfa893167c7d9d3f6dc7a2c0d197e47f43a
Security Fix Commit FIX COMMIT
https://github.com/ronf/asyncssh/commit/c161e26cdc0d41b745b63d9f17b437f073bf7ba4
AsyncSSH Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/asyncssh/PYSEC-2018-108.yaml
AsyncSSH Source Repository REPOSITORY
https://github.com/ronf/asyncssh
groups.google.com/forum/ WEB
https://groups.google.com/forum/#!msg/asyncssh-announce/57_5O7kiHSA/8BXZ_hxHAQAJ

Frequently Asked Questions

What is CVE-2018-7749?
CVE-2018-7749 is a security vulnerability in AsyncSSH involving AsyncSSH SSH Server Authentication Bypass under CWE-287: Improper Authentication.
Which AsyncSSH versions are affected?
Affected versions include releases prior to 1.12.1 across affected packages: AsyncSSH.
What version fixes CVE-2018-7749?
Upgrading to 1.12.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is AsyncSSH affected?
Yes, AsyncSSH is affected in releases prior to 1.12.1. Upgrade your dependency to 1.12.1 or later.
What is the CVSS score of CVE-2018-7749?
CVE-2018-7749 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2018-7749?
CVE-2018-7749 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check PyPI dependencies for CVE-2018-7749?
Run the dependency tree command: 'pip show AsyncSSH'. 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-97cv-6pjf-5f9q",
  "modified" : "2024-09-04T20:55:08Z",
  "published" : "2022-05-14T01:29:12Z",
  "aliases" : [ "CVE-2018-7749" ],
  "summary" : "AsyncSSH SSH Server Authentication Bypass",
  "details" : "The SSH server implementation of AsyncSSH before 1.12.1 does not properly check whether authentication is completed before processing other requests. A customized SSH client can simply skip the authentication step.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "AsyncSSH"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.12.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-7749"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ronf/asyncssh/commit/16e6ebfa893167c7d9d3f6dc7a2c0d197e47f43a"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ronf/asyncssh/commit/c161e26cdc0d41b745b63d9f17b437f073bf7ba4"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/asyncssh/PYSEC-2018-108.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ronf/asyncssh"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/forum/#!msg/asyncssh-announce/57_5O7kiHSA/8BXZ_hxHAQAJ"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-08-03T22:53:06Z",
    "nvd_published_at" : "2018-03-12T19:29:00Z"
  }
}