CVE-2015-8855: Semver Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-x6fg-f45m-jf5q
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CVSS 7.5
CWE-1333
Published
Advisory Summary

CVE-2015-8855 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-1333: Inefficient Regular Expression Complexity) affecting Semver libraries in the npm ecosystem. The issue involves regular expression denial of service in semver. Remediation is available by upgrading affected packages to version 4.3.2.

CVE-2015-8855 at a Glance

CVE Identifier CVE-2015-8855
GHSA Identifier GHSA-x6fg-f45m-jf5q
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-1333: Inefficient Regular Expression Complexity
Affected Product Semver
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:3.0/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-2015-8855

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

semver fixed: 4.3.2 
npm install semver@4.3.2
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 semver

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2015-8855, inspect your project dependencies using npm:

npm ls semver

Analyze the terminal output to locate any version of Semver in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.3.2), your application is affected.

Note: The npm ls semver 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 Semver, 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

Versions 4.3.1 and earlier of `semver` are affected by a regular expression denial of service vulnerability when extremely long version strings are parsed. ## Recommendation Update to version 4.3.2 or later

CVE-2015-8855 Affected Semver Versions

1 component(s)
Fixed Versions:
4.3.2
Product / Package Ecosystem Affected Versions Fixed Version
semver
npm/semver
npm
≥ 1.0.4
< 4.3.2
4.3.2

References

NVD — CVE-2015-8855 NVD
https://nvd.nist.gov/vuln/detail/CVE-2015-8855
Semver Source Repository REPOSITORY
https://github.com/github/advisory-database/pull/7102
Security Fix Commit FIX COMMIT
https://github.com/npm/node-semver/commit/5c4c9f6e26c7052a42b5ced2a7481c5c9b4363a0
Security Fix Commit FIX COMMIT
https://github.com/npm/node-semver/commit/c80180d8341a8ada0236815c29a2be59864afd70
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-x6fg-f45m-jf5q
Semver Source Repository REPOSITORY
https://github.com/npm/node-semver
www.npmjs.com/advisories/31 WEB
https://www.npmjs.com/advisories/31
www.owasp.org/index.php/regular_e... WEB
https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS
Semver Security Information SECURITY
http://www.openwall.com/lists/oss-security/2016/04/20/11
Semver Security Information SECURITY
http://www.securityfocus.com/bid/86957

Frequently Asked Questions

What is CVE-2015-8855?
CVE-2015-8855 is a security vulnerability in Semver involving Regular Expression Denial of Service in semver under CWE-1333: Inefficient Regular Expression Complexity.
Which Semver versions are affected?
Affected versions include releases prior to 4.3.2 across affected packages: semver.
What version fixes CVE-2015-8855?
Upgrading to 4.3.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is semver affected?
Yes, semver is affected in releases prior to 4.3.2. Upgrade your dependency to 4.3.2 or later.
What is the CVSS score of CVE-2015-8855?
CVE-2015-8855 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:N/I:N/A:H.
What CWE is associated with CVE-2015-8855?
CVE-2015-8855 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-2015-8855?
Run the dependency tree command: 'npm ls semver'. 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-x6fg-f45m-jf5q",
  "modified" : "2026-03-03T20:03:27Z",
  "published" : "2017-10-24T18:33:36Z",
  "aliases" : [ "CVE-2015-8855" ],
  "summary" : "Regular Expression Denial of Service in semver",
  "details" : "Versions 4.3.1 and earlier of `semver` are affected by a regular expression denial of service vulnerability when extremely long version strings are parsed.\n\n\n\n## Recommendation\n\nUpdate to version 4.3.2 or later",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "semver"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.4"
      }, {
        "fixed" : "4.3.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2015-8855"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/github/advisory-database/pull/7102"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/node-semver/commit/5c4c9f6e26c7052a42b5ced2a7481c5c9b4363a0"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/node-semver/commit/c80180d8341a8ada0236815c29a2be59864afd70"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-x6fg-f45m-jf5q"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/npm/node-semver"
  }, {
    "type" : "WEB",
    "url" : "https://www.npmjs.com/advisories/31"
  }, {
    "type" : "WEB",
    "url" : "https://www.owasp.org/index.php/Regular_expression_Denial_of_Service_-_ReDoS"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2016/04/20/11"
  }, {
    "type" : "WEB",
    "url" : "http://www.securityfocus.com/bid/86957"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1333" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-06-16T22:02:25Z",
    "nvd_published_at" : "2017-01-23T21:59:00Z"
  }
}