CVE-2025-64097 Overview
CVE-2025-64097 is an Insecure Random Number Generation vulnerability affecting NervesHub, a web service that enables over-the-air (OTA) firmware updates for IoT devices. The vulnerability exists in versions 1.0.0 through 2.2.x and allows attackers to brute-force user API tokens due to the predictable format of previously issued tokens.
The tokens included user-identifiable components and were not cryptographically secure, making them susceptible to guessing or enumeration attacks. This weakness in token generation could enable unauthorized access to user accounts or protected API actions, potentially compromising device firmware update processes across an organization's entire IoT fleet.
Critical Impact
Attackers can brute-force predictable API tokens to gain unauthorized access to user accounts and API actions, potentially enabling malicious firmware deployment to IoT devices in the field.
Affected Products
- NervesHub version 1.0.0 through 2.2.x
- NervesHub Web Application (nerves_hub_web)
Discovery Timeline
- 2026-01-22 - CVE CVE-2025-64097 published to NVD
- 2026-01-22 - Last updated in NVD database
Technical Details for CVE-2025-64097
Vulnerability Analysis
This vulnerability stems from CWE-330: Use of Insufficiently Random Values. The token generation mechanism in NervesHub prior to version 2.3.0 used predictable patterns that incorporated user-identifiable components. This design flaw meant that tokens were not cryptographically random, enabling attackers to deduce or enumerate valid tokens through systematic guessing.
The impact is particularly severe in IoT environments where NervesHub manages firmware updates. Successful exploitation could allow an attacker to authenticate as a legitimate user and perform API actions including pushing firmware updates to devices. Given the network-accessible nature of the service and the lack of privilege requirements for exploitation, this vulnerability presents a significant risk to organizations relying on NervesHub for device management.
Root Cause
The root cause is the use of insufficiently random values when generating API tokens. The original implementation created tokens using a predictable format that included user-identifiable components rather than cryptographically secure random bytes. Without proper randomness, the token space became small enough to make brute-force attacks feasible.
Additionally, tokens were stored in plaintext in the database, meaning a database compromise would directly expose all valid tokens without requiring any additional cracking effort.
Attack Vector
The attack vector is network-based, requiring no authentication or user interaction. An attacker can remotely target the NervesHub API endpoints by systematically attempting to authenticate using generated token guesses. The predictable token format significantly reduces the search space compared to properly randomized tokens, making brute-force attacks practical.
The attacker would typically:
- Identify the NervesHub instance exposed on the network
- Analyze the predictable token format to understand its structure
- Generate candidate tokens incorporating known or guessed user identifiers
- Enumerate API endpoints using the candidate tokens until successful authentication occurs
- Leverage the compromised token to access user accounts or perform privileged API actions
For technical details on the vulnerability and the fix implementation, see the GitHub Security Advisory GHSA-m9vj-776q-vc8m and the Pull Request #2024.
Detection Methods for CVE-2025-64097
Indicators of Compromise
- Abnormally high volume of failed API authentication attempts from single IP addresses
- Sequential or patterned token values appearing in authentication logs
- Successful API authentications from unexpected geographic locations or IP ranges
- Unusual API activity patterns following periods of authentication failures
Detection Strategies
- Implement rate limiting on API authentication endpoints to detect and block brute-force attempts
- Monitor authentication logs for patterns indicating token enumeration (repeated failures followed by success)
- Deploy anomaly detection on API usage to identify accounts exhibiting unusual post-authentication behavior
- Review database access logs for signs of unauthorized token extraction
Monitoring Recommendations
- Enable detailed logging for all API authentication events including source IP, timestamp, and token metadata
- Set up alerts for authentication failure thresholds that may indicate active brute-force attempts
- Monitor for any firmware deployment activities initiated through the API and correlate with expected administrative actions
- Implement network-level monitoring to detect connections from unexpected sources to the NervesHub instance
How to Mitigate CVE-2025-64097
Immediate Actions Required
- Upgrade NervesHub to version 2.3.0 or later immediately
- Regenerate all existing API tokens after upgrading to ensure cryptographically secure tokens are in use
- Review API access logs for signs of unauthorized access using compromised tokens
- Implement firewall rules to restrict NervesHub access to trusted networks until upgrade is complete
- Invalidate all existing sessions and require users to re-authenticate
Patch Information
Version 2.3.0 of NervesHub addresses this vulnerability with the following security improvements:
- Cryptographically secure token generation: Tokens are now generated using :crypto.strong_rand_bytes/1, ensuring proper randomness
- Token hashing: Tokens are hashed before database storage, preventing misuse even if the database is compromised
- Context-aware token storage: The system now distinguishes between session tokens and API tokens for improved security management
The fix is available via the GitHub Release Version 2.3.0.
Workarounds
- Restrict network access to the NervesHub server using firewall rules to limit exposure to trusted IP ranges only
- Implement aggressive rate limiting on API authentication endpoints at the network or application level
- Deploy a Web Application Firewall (WAF) to detect and block brute-force patterns against the API
- Monitor and alert on any API authentication activity while awaiting the upgrade
# Example: Restrict NervesHub access using iptables (temporary mitigation)
# Allow access only from trusted internal network
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
# Alternatively, use ufw for simpler firewall management
ufw allow from 10.0.0.0/8 to any port 443
ufw deny 443
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
