CVE-2021-27515: Url parse Path Traversal Vulnerability

MODERATE
Advisory Identifier: GHSA-9m6j-fcg5-2442
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CVSS 5.3
CWE-23
Published
Advisory Summary

CVE-2021-27515 is a MODERATE (CVSS 5.3) path traversal vulnerability (CWE-23: Relative Path Traversal) affecting Url parse libraries in the npm ecosystem. The issue involves path traversal in url-parse. Remediation is available by upgrading affected packages to version 1.5.0.

CVE-2021-27515 at a Glance

CVE Identifier CVE-2021-27515
GHSA Identifier GHSA-9m6j-fcg5-2442
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-23: Relative Path Traversal
Affected Product Url parse
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

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:L/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 None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-27515

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

url-parse fixed: 1.5.0 
npm install url-parse@1.5.0
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 url-parse

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-27515, inspect your project dependencies using npm:

npm ls url-parse

Analyze the terminal output to locate any version of Url parse in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.0), your application is affected.

Note: The npm ls url-parse 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-23: Relative Path Traversal, where the product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory. In Url parse, 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

url-parse before 1.5.0 mishandles certain uses of backslash such as http:\/ and interprets the URI as a relative path.

CVE-2021-27515 Affected Url parse Versions

1 component(s)
Fixed Versions:
1.5.0
Product / Package Ecosystem Affected Versions Fixed Version
url-parse
npm/url-parse
npm
≥ 0.1.0
< 1.5.0
1.5.0

References

NVD — CVE-2021-27515 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-27515
Url parse Source Repository REPOSITORY
https://github.com/github/advisory-database/pull/6763
Url parse Source Repository REPOSITORY
https://github.com/unshiftio/url-parse/pull/197
Security Fix Commit FIX COMMIT
https://github.com/unshiftio/url-parse/commit/d1e7e8822f26e8a49794b757123b51386325b2b0
advisory.checkmarx.net/advisory/cx-2021-43... WEB
https://advisory.checkmarx.net/advisory/CX-2021-4306
Url parse Source Repository REPOSITORY
https://github.com/unshiftio/url-parse
Url parse Source Repository REPOSITORY
https://github.com/unshiftio/url-parse/compare/1.4.7...1.5.0
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2023/02/msg00030.html

Frequently Asked Questions

What is CVE-2021-27515?
CVE-2021-27515 is a security vulnerability in Url parse involving Path traversal in url-parse under CWE-23: Relative Path Traversal.
Which Url parse versions are affected?
Affected versions include releases prior to 1.5.0 across affected packages: url-parse.
What version fixes CVE-2021-27515?
Upgrading to 1.5.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is url-parse affected?
Yes, url-parse is affected in releases prior to 1.5.0. Upgrade your dependency to 1.5.0 or later.
What is the CVSS score of CVE-2021-27515?
CVE-2021-27515 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2021-27515?
CVE-2021-27515 is classified under CWE-23: Relative Path Traversal (The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory.).
How can I check npm dependencies for CVE-2021-27515?
Run the dependency tree command: 'npm ls url-parse'. 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-9m6j-fcg5-2442",
  "modified" : "2026-02-03T22:11:36Z",
  "published" : "2021-05-06T16:10:51Z",
  "aliases" : [ "CVE-2021-27515" ],
  "summary" : "Path traversal in url-parse",
  "details" : "url-parse before 1.5.0 mishandles certain uses of backslash such as http:\\/ and interprets the URI as a relative path.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "url-parse"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.1.0"
      }, {
        "fixed" : "1.5.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-27515"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/github/advisory-database/pull/6763"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/unshiftio/url-parse/pull/197"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/unshiftio/url-parse/commit/d1e7e8822f26e8a49794b757123b51386325b2b0"
  }, {
    "type" : "WEB",
    "url" : "https://advisory.checkmarx.net/advisory/CX-2021-4306"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/unshiftio/url-parse"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/unshiftio/url-parse/compare/1.4.7...1.5.0"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2023/02/msg00030.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-23" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-03-22T21:04:52Z",
    "nvd_published_at" : "2021-02-22T00:15:00Z"
  }
}