CVE-2021-23446 – This vulnerability allows attackers to cause a ... (How to Fix)

Q: What is the severity of CVE-2021-23446?

CVE-2021-23446 has a CVSS score of 7.5 (HIGH). This vulnerability allows attackers to cause a Denial of Service (DoS) by exploiting a regular expression in the Handsontable JavaScript library. Applications using vulnerable versions of Handsontable can be rendered unresponsive when processing malicious input. This affects any web application or system that uses the vulnerable Handsontable package.

📋 TL;DR

This vulnerability allows attackers to cause a Denial of Service (DoS) by exploiting a regular expression in the Handsontable JavaScript library. Applications using vulnerable versions of Handsontable can be rendered unresponsive when processing malicious input. This affects any web application or system that uses the vulnerable Handsontable package.

💻 Affected Systems

Products:

Handsontable JavaScript library
Applications using Handsontable via .NET packages
Applications using Handsontable via Java WebJars

Versions: All versions before 10.0.0

Operating Systems: All operating systems running web applications with Handsontable

Default Config Vulnerable: ⚠️ Yes

Notes: The vulnerability exists in the core Handsontable library and affects all implementations regardless of configuration.

📦 What is this software?

Handsontable by Handsontable

View all CVEs affecting Handsontable →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete application unavailability due to CPU exhaustion from ReDoS, potentially affecting all users of the application.

🟠

Likely Case

Degraded performance or temporary unavailability of specific application components that use the vulnerable isNumeric function.

🟢

If Mitigated

Minimal impact with proper input validation and rate limiting in place before data reaches the vulnerable function.

🌐 Internet-Facing: HIGH - Web applications using Handsontable are directly accessible to attackers who can send malicious payloads.

🏢 Internal Only: MEDIUM - Internal applications are still vulnerable but have reduced attack surface compared to internet-facing systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

ReDoS vulnerabilities are typically easy to exploit by sending specially crafted input to trigger exponential backtracking in the regular expression.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 10.0.0 and later

Vendor Advisory: https://github.com/handsontable/handsontable/issues/8752

Restart Required: Yes

Instructions:

1. Update Handsontable package to version 10.0.0 or later. 2. For .NET: Update to patched Handsontable package. 3. For Java WebJars: Update to patched versions. 4. Restart the application server.

🔧 Temporary Workarounds

Input Validation Filter

all

Implement server-side validation to reject or sanitize input before it reaches the vulnerable isNumeric function.

Rate Limiting

all

Implement rate limiting on endpoints that process user input to prevent DoS attacks.

🧯 If You Can't Patch

Implement Web Application Firewall (WAF) rules to block malicious patterns targeting ReDoS vulnerabilities
Monitor application performance metrics and set alerts for abnormal CPU usage patterns

🔍 How to Verify

Check if Vulnerable:

Check package.json or dependency files for Handsontable version. If version is below 10.0.0, the system is vulnerable.

Check Version:

npm list handsontable (for Node.js) or check package manager for .NET/Java implementations

Verify Fix Applied:

Confirm Handsontable version is 10.0.0 or higher in package.json and verify the application loads without errors.

📡 Detection & Monitoring

Log Indicators:

High CPU usage spikes
Application timeouts or slow response times
Repeated failed requests to endpoints using Handsontable

Network Indicators:

Unusually large number of requests to endpoints processing numeric input
Patterns of requests with specially crafted numeric-like strings

SIEM Query:

source="application_logs" AND (message="CPU spike" OR message="timeout" OR message="slow response") AND component="handsontable"

📊 Metadata

CVE ID: CVE-2021-23446

CVSS v3 Score: 7.5 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-1333

Published: September 29, 2021

Last Updated: November 21, 2024

🔗 References

https://github.com/handsontable/handsontable/issues/8752 Third Party Advisory
https://github.com/handsontable/handsontable/pull/8742 Patch,Third Party Advisory
https://snyk.io/vuln/SNYK-DOTNET-HANDSONTABLE-1726793 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARS-1726795 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWER-1726796 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWERGITHUBHANDSONTABLE-1726794 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1726797 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JS-HANDSONTABLE-1726770 Exploit,Third Party Advisory
https://github.com/handsontable/handsontable/issues/8752 Third Party Advisory
https://github.com/handsontable/handsontable/pull/8742 Patch,Third Party Advisory
https://snyk.io/vuln/SNYK-DOTNET-HANDSONTABLE-1726793 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARS-1726795 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWER-1726796 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSBOWERGITHUBHANDSONTABLE-1726794 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1726797 Exploit,Third Party Advisory
https://snyk.io/vuln/SNYK-JS-HANDSONTABLE-1726770 Exploit,Third Party Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2021-23446, you might also want to check these: