CVE-2019-1020001: Yard Path Traversal Vulnerability

HIGH
Advisory Identifier: GHSA-xfhh-rx56-rxcr
Share
CVSS 7.5
CWE-22
Published
Advisory Summary

CVE-2019-1020001 is a HIGH (CVSS 7.5) path traversal vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Yard libraries in the RubyGems ecosystem. The issue involves path traversal vulnerability that affects yard. Remediation is available by upgrading affected packages to version 0.9.20.

CVE-2019-1020001 at a Glance

CVE Identifier CVE-2019-1020001
GHSA Identifier GHSA-xfhh-rx56-rxcr
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 Yard
Package Ecosystem RubyGems
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-2019-1020001

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

yard fixed: 0.9.20 
Upgrade yard to 0.9.20
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 yard

How to Check if You Are Affected

To determine whether your application is affected by CVE-2019-1020001, inspect your project dependencies for Yard:

inspect dependencies for yard

Analyze the terminal output to locate any version of Yard in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.9.20), 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-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 Yard, 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

## Possible arbitrary path traversal and file access via `yard server` ### Impact A path traversal vulnerability was discovered in YARD <= 0.9.19 when using `yard server` to serve documentation. This bug would allow unsanitized HTTP requests to access arbitrary files on the machine of a yard server host under certain conditions. Thanks to CuongMX from Viettel Cyber Security for discovering this vulnerability. ### Patches Please upgrade to YARD v0.9.20 immediately if you are relying on yard server to host documentation in any untrusted environments. ### Workarounds For users who cannot upgrade, it is possible to perform path sanitization of HTTP requests at your webserver level. WEBrick, for example, can perform such sanitization by default (which you can use via `yard server -s webrick`), as can certain rules in your webserver configuration.

CVE-2019-1020001 Affected Yard Versions

1 component(s)
Fixed Versions:
0.9.20
Product / Package Ecosystem Affected Versions Fixed Version
yard
gem/yard
RubyGems
< 0.9.20
0.9.20

References

GitHub Advisory / Wiki ADVISORY
https://github.com/lsegal/yard/security/advisories/GHSA-xfhh-rx56-rxcr
NVD — CVE-2019-1020001 NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-1020001
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-xfhh-rx56-rxcr
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2024/03/msg00006.html

Frequently Asked Questions

What is CVE-2019-1020001?
CVE-2019-1020001 is a security vulnerability in Yard involving Path Traversal vulnerability that affects yard under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which Yard versions are affected?
Affected versions include releases prior to 0.9.20 across affected packages: yard.
What version fixes CVE-2019-1020001?
Upgrading to 0.9.20 (or the latest patched release for your respective branch) resolves the vulnerability.
Is yard affected?
Yes, yard is affected in releases prior to 0.9.20. Upgrade your dependency to 0.9.20 or later.
What is the CVSS score of CVE-2019-1020001?
CVE-2019-1020001 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-2019-1020001?
CVE-2019-1020001 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 RubyGems dependencies for CVE-2019-1020001?
Run the dependency tree command: 'inspect dependencies for yard'. 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-xfhh-rx56-rxcr",
  "modified" : "2024-03-07T00:30:48Z",
  "published" : "2019-07-02T15:28:38Z",
  "aliases" : [ "CVE-2019-1020001" ],
  "summary" : "Path Traversal vulnerability that affects yard",
  "details" : "## Possible arbitrary path traversal and file access via `yard server`\n\n### Impact\n\nA path traversal vulnerability was discovered in YARD <= 0.9.19 when using `yard server` to serve documentation. This bug would allow unsanitized HTTP requests to access arbitrary files on the machine of a yard server host under certain conditions.\n\nThanks to CuongMX from Viettel Cyber Security for discovering this vulnerability.\n\n### Patches\n\nPlease upgrade to YARD v0.9.20 immediately if you are relying on yard server to host documentation in any untrusted environments.\n\n### Workarounds\n\nFor users who cannot upgrade, it is possible to perform path sanitization of HTTP requests at your webserver level. WEBrick, for example, can perform such sanitization by default (which you can use via `yard server -s webrick`), as can certain rules in your webserver configuration.",
  "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" : "RubyGems",
      "name" : "yard"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.9.20"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/lsegal/yard/security/advisories/GHSA-xfhh-rx56-rxcr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2019-1020001"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-xfhh-rx56-rxcr"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2024/03/msg00006.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T22:03:08Z",
    "nvd_published_at" : "2019-07-29T13:15:00Z"
  }
}