CVE-2018-3737: Sshpk Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-2m39-62fm-q8r3
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CVSS 7.5
CWE-185 CWE-770
Published
Advisory Summary

CVE-2018-3737 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-185: Incorrect Regular Expression) affecting Sshpk libraries in the npm ecosystem. The issue involves regular expression denial of service in sshpk. Remediation is available by upgrading affected packages to version 1.13.2.

CVE-2018-3737 at a Glance

CVE Identifier CVE-2018-3737
GHSA Identifier GHSA-2m39-62fm-q8r3
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-185: Incorrect Regular Expression
Affected Product Sshpk
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:N/I:N/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 None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2018-3737

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

sshpk fixed: 1.13.2 
npm install sshpk@1.13.2
Verify Direct and Transitive Dependencies

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

npm ls sshpk

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2018-3737, inspect your project dependencies using npm:

npm ls sshpk

Analyze the terminal output to locate any version of Sshpk in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.13.2), your application is affected.

Note: The npm ls sshpk command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-185: Incorrect Regular Expression, where the product specifies a regular expression in a way that causes data to be improperly matched or compared. In Sshpk, 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

Versions of `sshpk` before 1.13.2 or 1.14.1 are vulnerable to regular expression denial of service when parsing crafted invalid public keys. ## Recommendation Update to version 1.13.2, 1.14.1 or later.

CVE-2018-3737 Affected Sshpk Versions

1 component(s)
Fixed Versions:
1.13.2
Product / Package Ecosystem Affected Versions Fixed Version
sshpk
npm/sshpk
npm
< 1.13.2
1.13.2

References

NVD — CVE-2018-3737 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-3737
Security Fix Commit FIX COMMIT
https://github.com/joyent/node-sshpk/commit/46065d38a5e6d1bccf86d3efb2fb83c14e3f9957
hackerone.com/reports/319593 WEB
https://hackerone.com/reports/319593
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-2m39-62fm-q8r3
Sshpk Source Repository REPOSITORY
https://github.com/joyent/node-sshpk/blob/v1.13.1/lib/formats/ssh.js#L17
www.npmjs.com/advisories/606 WEB
https://www.npmjs.com/advisories/606

Frequently Asked Questions

What is CVE-2018-3737?
CVE-2018-3737 is a security vulnerability in Sshpk involving Regular Expression Denial of Service in sshpk under CWE-185: Incorrect Regular Expression.
Which Sshpk versions are affected?
Affected versions include releases prior to 1.13.2 across affected packages: sshpk.
What version fixes CVE-2018-3737?
Upgrading to 1.13.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is sshpk affected?
Yes, sshpk is affected in releases prior to 1.13.2. Upgrade your dependency to 1.13.2 or later.
What is the CVSS score of CVE-2018-3737?
CVE-2018-3737 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2018-3737?
CVE-2018-3737 is classified under CWE-185: Incorrect Regular Expression (The product specifies a regular expression in a way that causes data to be improperly matched or compared.).
How can I check npm dependencies for CVE-2018-3737?
Run the dependency tree command: 'npm ls sshpk'. 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-2m39-62fm-q8r3",
  "modified" : "2023-01-31T01:55:03Z",
  "published" : "2018-08-15T13:22:23Z",
  "aliases" : [ "CVE-2018-3737" ],
  "summary" : "Regular Expression Denial of Service in sshpk",
  "details" : "Versions of `sshpk` before 1.13.2 or 1.14.1 are vulnerable to regular expression denial of service when parsing crafted invalid public keys.\n\n\n## Recommendation\n\nUpdate to version 1.13.2, 1.14.1 or later.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "sshpk"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.13.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-3737"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/joyent/node-sshpk/commit/46065d38a5e6d1bccf86d3efb2fb83c14e3f9957"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/319593"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-2m39-62fm-q8r3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/joyent/node-sshpk/blob/v1.13.1/lib/formats/ssh.js#L17"
  }, {
    "type" : "WEB",
    "url" : "https://www.npmjs.com/advisories/606"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-185", "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T20:52:29Z",
    "nvd_published_at" : "2018-06-07T02:29:00Z"
  }
}