CVE-2019-25103: Simple markdown Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-gpvj-gp8c-c7p2
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CVSS 7.5
CWE-1333
Published
Advisory Summary

CVE-2019-25103 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-1333: Inefficient Regular Expression Complexity) affecting Simple markdown libraries in the npm ecosystem. The issue involves regular expression denial of service in simple-markdown. Remediation is available by upgrading affected packages to version 0.5.2.

CVE-2019-25103 at a Glance

CVE Identifier CVE-2019-25103
GHSA Identifier GHSA-gpvj-gp8c-c7p2
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-1333: Inefficient Regular Expression Complexity
Affected Product Simple markdown
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-2019-25103

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

simple-markdown fixed: 0.5.2 
npm install simple-markdown@0.5.2
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 simple-markdown

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2019-25103, inspect your project dependencies using npm:

npm ls simple-markdown

Analyze the terminal output to locate any version of Simple markdown in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.5.2), your application is affected.

Note: The npm ls simple-markdown 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-1333: Inefficient Regular Expression Complexity, where the product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential. In Simple markdown, 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

A vulnerability has been found in simple-markdown 0.5.1 and classified as problematic. Affected by this vulnerability is an unknown functionality of the file simple-markdown.js. The manipulation leads to inefficient regular expression complexity. The attack can be launched remotely. Upgrading to version 0.5.2 is able to address this issue. The name of the patch is 89797fef9abb4cab2fb76a335968266a92588816. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-220639.

CVE-2019-25103 Affected Simple markdown Versions

1 component(s)
Fixed Versions:
0.5.2
Product / Package Ecosystem Affected Versions Fixed Version
simple-markdown
npm/simple-markdown
npm
< 0.5.2
0.5.2

References

NVD — CVE-2019-25103 NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-25103
Simple markdown Source Repository REPOSITORY
https://github.com/Khan/simple-markdown/issues/71
Security Fix Commit FIX COMMIT
https://github.com/ariabuckles/simple-markdown/commit/89797fef9abb4cab2fb76a335968266a92588816
Simple markdown Source Repository REPOSITORY
https://github.com/ariabuckles/simple-markdown
Simple markdown Release RELEASE
https://github.com/ariabuckles/simple-markdown/releases/tag/0.5.2
snyk.io/vuln/snyk-js-simple... WEB
https://snyk.io/vuln/SNYK-JS-SIMPLEMARKDOWN-460540
vuldb.com/ WEB
https://vuldb.com/?ctiid.220639
vuldb.com/ WEB
https://vuldb.com/?id.220639

Frequently Asked Questions

What is CVE-2019-25103?
CVE-2019-25103 is a security vulnerability in Simple markdown involving Regular Expression Denial of Service in simple-markdown under CWE-1333: Inefficient Regular Expression Complexity.
Which Simple markdown versions are affected?
Affected versions include releases prior to 0.5.2 across affected packages: simple-markdown.
What version fixes CVE-2019-25103?
Upgrading to 0.5.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is simple-markdown affected?
Yes, simple-markdown is affected in releases prior to 0.5.2. Upgrade your dependency to 0.5.2 or later.
What is the CVSS score of CVE-2019-25103?
CVE-2019-25103 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-2019-25103?
CVE-2019-25103 is classified under CWE-1333: Inefficient Regular Expression Complexity (The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.).
How can I check npm dependencies for CVE-2019-25103?
Run the dependency tree command: 'npm ls simple-markdown'. 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-gpvj-gp8c-c7p2",
  "modified" : "2026-02-03T17:53:00Z",
  "published" : "2023-02-12T15:30:24Z",
  "aliases" : [ "CVE-2019-25103" ],
  "summary" : "Regular Expression Denial of Service in simple-markdown",
  "details" : "A vulnerability has been found in simple-markdown 0.5.1 and classified as problematic. Affected by this vulnerability is an unknown functionality of the file simple-markdown.js. The manipulation leads to inefficient regular expression complexity. The attack can be launched remotely. Upgrading to version 0.5.2 is able to address this issue. The name of the patch is 89797fef9abb4cab2fb76a335968266a92588816. It is recommended to upgrade the affected component. The associated identifier of this vulnerability is VDB-220639.",
  "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" : "simple-markdown"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.5.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2019-25103"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Khan/simple-markdown/issues/71"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ariabuckles/simple-markdown/commit/89797fef9abb4cab2fb76a335968266a92588816"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ariabuckles/simple-markdown"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ariabuckles/simple-markdown/releases/tag/0.5.2"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-JS-SIMPLEMARKDOWN-460540"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/?ctiid.220639"
  }, {
    "type" : "WEB",
    "url" : "https://vuldb.com/?id.220639"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1333" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-02-14T01:02:08Z",
    "nvd_published_at" : "2023-02-12T15:15:00Z"
  }
}