CVE-2018-17785: Blynk server Path Traversal Vulnerability

HIGH
Advisory Identifier: GHSA-4r64-wf76-c53p
Share
CVSS 7.5
CWE-22
Published
Advisory Summary

CVE-2018-17785 is a HIGH (CVSS 7.5) path traversal vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Blynk server libraries in the Maven ecosystem. The issue involves in blynk-server a directory traversal exists. Remediation is available by upgrading affected packages to version 0.39.7.

CVE-2018-17785 at a Glance

CVE Identifier CVE-2018-17785
GHSA Identifier GHSA-4r64-wf76-c53p
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product Blynk server
Package Ecosystem Maven
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:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

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 None (I:N)
Availability None (A:N)

How to Fix CVE-2018-17785

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

com.github.blynkkk:blynk-server fixed: 0.39.7 
<dependency>
    <groupId>com.github.blynkkk</groupId>
    <artifactId>blynk-server</artifactId>
    <version>0.39.7</version>
</dependency>
Verify Direct and Transitive Dependencies

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

mvn dependency:tree -Dincludes=com.github.blynkkk

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2018-17785, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=com.github.blynkkk

Analyze the terminal output to locate any version of Blynk server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.39.7), your application is affected.

Note: The mvn dependency:tree -Dincludes=com.github.blynkkk command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In Blynk server, 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

In blynk-server in Blynk before 0.39.7, Directory Traversal exists via a ../ in a URI that has /static or /static/js at the beginning, as demonstrated by reading the /etc/passwd file.

CVE-2018-17785 Affected Blynk server Versions

1 component(s)
Fixed Versions:
0.39.7
Product / Package Ecosystem Affected Versions Fixed Version
com.github.blynkkk:blynk-server
maven/com.github.blynkkk/blynk-server
Maven
< 0.39.7
0.39.7

References

NVD — CVE-2018-17785 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-17785
Blynk server Source Repository REPOSITORY
https://github.com/blynkkk/blynk-server/issues/1256
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-4r64-wf76-c53p
Blynk server Source Repository REPOSITORY
https://github.com/blynkkk/blynk-server
Blynk server Release RELEASE
https://github.com/blynkkk/blynk-server/releases/tag/v0.39.7

Frequently Asked Questions

What is CVE-2018-17785?
CVE-2018-17785 is a security vulnerability in Blynk server involving In blynk-server a Directory Traversal exists under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which Blynk server versions are affected?
Affected versions include releases prior to 0.39.7 across affected packages: com.github.blynkkk:blynk-server.
What version fixes CVE-2018-17785?
Upgrading to 0.39.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is blynk-server affected?
Yes, com.github.blynkkk:blynk-server is affected in releases prior to 0.39.7. Upgrade your dependency to 0.39.7 or later.
What is the CVSS score of CVE-2018-17785?
CVE-2018-17785 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2018-17785?
CVE-2018-17785 is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.).
How can I check Maven dependencies for CVE-2018-17785?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=com.github.blynkkk'. 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-4r64-wf76-c53p",
  "modified" : "2022-04-27T14:26:22Z",
  "published" : "2018-10-17T19:52:52Z",
  "aliases" : [ "CVE-2018-17785" ],
  "summary" : "In blynk-server a Directory Traversal exists",
  "details" : "In blynk-server in Blynk before 0.39.7, Directory Traversal exists via a ../ in a URI that has /static or /static/js at the beginning, as demonstrated by reading the /etc/passwd file.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "com.github.blynkkk:blynk-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.39.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-17785"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/blynkkk/blynk-server/issues/1256"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-4r64-wf76-c53p"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/blynkkk/blynk-server"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/blynkkk/blynk-server/releases/tag/v0.39.7"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T20:58:56Z",
    "nvd_published_at" : null
  }
}