CVE-2026-25639 – This vulnerability in Axios allows attackers to... (How to Fix)

Q: What is the severity of CVE-2026-25639?

CVE-2026-25639 has a CVSS score of 7.5 (HIGH). This vulnerability in Axios allows attackers to cause denial of service by providing malicious configuration objects containing __proto__ as an own property. When processed by the mergeConfig function, this triggers a TypeError that crashes the application. Any application using vulnerable versions of Axios for HTTP requests is affected.

📋 TL;DR

This vulnerability in Axios allows attackers to cause denial of service by providing malicious configuration objects containing __proto__ as an own property. When processed by the mergeConfig function, this triggers a TypeError that crashes the application. Any application using vulnerable versions of Axios for HTTP requests is affected.

💻 Affected Systems

Products:

axios

Versions: All versions prior to 1.13.5

Operating Systems: All platforms where Node.js or browsers run

Default Config Vulnerable: ⚠️ Yes

Notes: Vulnerability triggers when processing configuration objects created via JSON.parse() with __proto__ property.

📦 What is this software?

Axios by Axios

View all CVEs affecting Axios →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete application crash and denial of service, potentially affecting all users of the vulnerable service.

🟠

Likely Case

Application crashes when processing malicious requests, causing service disruption until restart.

🟢

If Mitigated

Minimal impact with proper input validation and updated Axios version.

🌐 Internet-Facing: HIGH - Attackers can exploit this remotely by sending malicious HTTP requests.

🏢 Internal Only: MEDIUM - Internal users could exploit if they can send requests to vulnerable endpoints.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation requires sending malicious configuration objects to endpoints using Axios. The advisory includes proof-of-concept details.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 1.13.5

Vendor Advisory: https://github.com/axios/axios/security/advisories/GHSA-43fc-jf86-j433

Restart Required: Yes

Instructions:

1. Update package.json to specify axios version 1.13.5 or higher. 2. Run npm update axios or yarn upgrade axios. 3. Restart your application.

🔧 Temporary Workarounds

Input validation for configuration objects

all

Validate and sanitize configuration objects before passing to Axios to remove __proto__ properties.

// JavaScript example: delete config.__proto__; before using axios

🧯 If You Can't Patch

Implement strict input validation to reject configuration objects containing __proto__ property.
Use web application firewall rules to block requests containing suspicious __proto__ patterns.

🔍 How to Verify

Check if Vulnerable:

Check package.json or run npm list axios to see if version is below 1.13.5.

Check Version:

npm list axios | grep axios

Verify Fix Applied:

Confirm axios version is 1.13.5 or higher using npm list axios and test with known malicious configuration.

📡 Detection & Monitoring

Log Indicators:

TypeError crashes in application logs related to mergeConfig function
Unusual HTTP requests containing __proto__ in payload

Network Indicators:

HTTP requests with JSON payloads containing __proto__ property

SIEM Query:

source="application.logs" AND "TypeError" AND "mergeConfig"

📊 Metadata

CVE ID: CVE-2026-25639

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-754

EPSS Score: 0.01% exploit probability (1.7th percentile)

Published: February 9, 2026

Last Updated: February 18, 2026

🔗 References

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