CVE-2026-35467 Overview
CVE-2026-35467 is a credential protection vulnerability affecting browser-based client applications where API keys stored in temporary browser storage are not properly marked as protected. This security flaw allows attackers to extract encryption credentials through the JavaScript console or by exploiting other browser-based errors, potentially leading to unauthorized access to protected resources.
Critical Impact
Exposed API keys can be extracted via JavaScript console access, enabling attackers to obtain encryption credentials and potentially compromise protected systems and data.
Affected Products
- CERT/CC CVE Client (browser-based component)
Discovery Timeline
- 2026-04-02 - CVE CVE-2026-35467 published to NVD
- 2026-04-02 - Last updated in NVD database
Technical Details for CVE-2026-35467
Vulnerability Analysis
This vulnerability is classified under CWE-522 (Insufficiently Protected Credentials), which describes scenarios where sensitive authentication data is stored or transmitted without adequate safeguards. In this case, API keys used for encryption operations are stored in temporary browser client storage without being marked with appropriate protection flags.
When credentials are not properly protected in browser storage, they become accessible through various attack vectors including direct JavaScript console manipulation, cross-site scripting (XSS) attacks, or through browser debugging tools. The lack of protection flags means the browser does not enforce restrictions on how and when these credentials can be accessed by scripts or extensions.
The vulnerability specifically affects how the application handles API key storage during active sessions. Without proper protection markers, malicious scripts or even legitimate error handling routines could inadvertently expose these sensitive credentials through console logging, error messages, or debugging output.
Root Cause
The root cause stems from improper implementation of credential storage in the browser client. API keys are stored in temporary client-side storage without utilizing available browser security mechanisms to protect sensitive data. The credentials lack appropriate protection attributes that would prevent their exposure through JavaScript access or error handling routines.
Attack Vector
An attacker could exploit this vulnerability through several methods:
Direct Console Access: If an attacker gains access to a user's browser session (physically or through social engineering), they can open the JavaScript console and directly query the unprotected storage to retrieve API keys.
XSS Exploitation: A cross-site scripting vulnerability in the same or related application could be leveraged to inject malicious JavaScript that extracts the unprotected credentials.
Error Message Leakage: Application errors or debugging output may inadvertently log or display the unprotected API keys, making them visible to attackers monitoring network traffic or error logs.
Browser Extension Attacks: Malicious browser extensions with appropriate permissions could access the unprotected storage and exfiltrate the credentials.
The extracted API keys could then be used to authenticate to backend services, decrypt protected data, or impersonate legitimate users.
Detection Methods for CVE-2026-35467
Indicators of Compromise
- Unusual API key usage patterns from unexpected IP addresses or geographic locations
- Multiple authentication attempts using the same API credentials from different sessions
- Unexpected access to encrypted resources or data protected by the compromised credentials
- Browser console access logs showing queries to credential storage objects
Detection Strategies
- Monitor API authentication logs for anomalous usage patterns that may indicate credential theft
- Implement rate limiting and alerting on API key usage to detect potential abuse
- Deploy browser security policies that restrict access to sensitive storage mechanisms
- Review application logs for error messages that may inadvertently expose credential information
Monitoring Recommendations
- Enable detailed logging for all API key authentication events
- Configure alerts for API access from new or unexpected client fingerprints
- Monitor for XSS attack attempts that could be used to extract credentials
- Implement session monitoring to detect potential credential harvesting activities
How to Mitigate CVE-2026-35467
Immediate Actions Required
- Review browser client implementations for proper credential protection flags
- Audit application code to ensure API keys are not exposed through console logging or error handlers
- Rotate any potentially compromised API keys as a precautionary measure
- Implement additional server-side validation for API key usage patterns
Patch Information
A fix has been proposed through GitHub Pull Request #39 in the CERT/CC CVE Client repository. Organizations using this component should review the pull request and apply the fix once merged, or implement the recommended changes manually.
For more information about the affected component, visit the CERT/CC CVE Client Repository.
Workarounds
- Implement Content Security Policy (CSP) headers to restrict JavaScript execution and reduce XSS attack surface
- Use secure, HttpOnly cookies for session management instead of client-side credential storage where possible
- Deploy browser security extensions or policies that prevent unauthorized console access in production environments
- Consider implementing short-lived tokens instead of persistent API keys for browser-based authentication
- Enable strict error handling to prevent credential exposure through debugging output
# Content Security Policy header example to reduce XSS attack surface
# Add to web server configuration
Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
