CVE-2018-1000162: Erusev/parsedown Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-qgpv-86r3-87fh
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2018-1000162 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Erusev/parsedown libraries in the Packagist ecosystem. The issue involves cross-site scripting in parsedown. Remediation is available by upgrading affected packages to version 1.7.0.

CVE-2018-1000162 at a Glance

CVE Identifier CVE-2018-1000162
GHSA Identifier GHSA-qgpv-86r3-87fh
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Erusev/parsedown
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 6.1

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:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2018-1000162

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

erusev/parsedown fixed: 1.7.0 
Upgrade erusev/parsedown to 1.7.0
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 erusev/parsedown

How to Check if You Are Affected

To determine whether your application is affected by CVE-2018-1000162, inspect your project dependencies for Erusev/parsedown:

inspect dependencies for erusev/parsedown

Analyze the terminal output to locate any version of Erusev/parsedown in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.7.0), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Erusev/parsedown, 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

Parsedown version prior to 1.7.0 contains a Cross Site Scripting (XSS) vulnerability in `setMarkupEscaped` for escaping HTML that can result in JavaScript code execution. This attack appears to be exploitable via specially crafted markdown that allows it to side step HTML escaping by breaking AST boundaries. This vulnerability appears to have been fixed in 1.7.0 and later.

CVE-2018-1000162 Affected Erusev/parsedown Versions

1 component(s)
Fixed Versions:
1.7.0
Product / Package Ecosystem Affected Versions Fixed Version
erusev/parsedown
 Packagist
< 1.7.0
1.7.0

References

NVD — CVE-2018-1000162 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-1000162
Erusev/parsedown Source Repository REPOSITORY
https://github.com/Roave/SecurityAdvisories/issues/44#issuecomment-368594409
Erusev/parsedown Source Repository REPOSITORY
https://github.com/erusev/parsedown/pull/495
Erusev/parsedown Source Repository REPOSITORY
https://github.com/FriendsOfPHP/security-advisories/blob/master/erusev/parsedown/CVE-2018-1000162.yaml
Erusev/parsedown Source Repository REPOSITORY
https://github.com/erusev/parsedown

Frequently Asked Questions

What is CVE-2018-1000162?
CVE-2018-1000162 is a security vulnerability in Erusev/parsedown involving Cross-site Scripting in Parsedown under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Erusev/parsedown versions are affected?
Affected versions include releases prior to 1.7.0 across affected packages: erusev/parsedown.
What version fixes CVE-2018-1000162?
Upgrading to 1.7.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is erusev/parsedown affected?
Yes, erusev/parsedown is affected in releases prior to 1.7.0. Upgrade your dependency to 1.7.0 or later.
What is the CVSS score of CVE-2018-1000162?
CVE-2018-1000162 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2018-1000162?
CVE-2018-1000162 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check Packagist dependencies for CVE-2018-1000162?
Run the dependency tree command: 'inspect dependencies for erusev/parsedown'. 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-qgpv-86r3-87fh",
  "modified" : "2022-03-30T18:26:22Z",
  "published" : "2022-03-30T18:26:22Z",
  "aliases" : [ "CVE-2018-1000162" ],
  "summary" : "Cross-site Scripting in Parsedown",
  "details" : "Parsedown version prior to 1.7.0 contains a Cross Site Scripting (XSS) vulnerability in `setMarkupEscaped` for escaping HTML that can result in JavaScript code execution. This attack appears to be exploitable via specially crafted markdown that allows it to side step HTML escaping by breaking AST boundaries. This vulnerability appears to have been fixed in 1.7.0 and later.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "erusev/parsedown"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.7.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-1000162"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Roave/SecurityAdvisories/issues/44#issuecomment-368594409"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/erusev/parsedown/pull/495"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/erusev/parsedown/CVE-2018-1000162.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/erusev/parsedown"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-03-30T18:26:22Z",
    "nvd_published_at" : null
  }
}