Denial-of-Service in NGINX JavaScript via Malformed HTTP Response

Executive Summary

This vulnerability exists in NGINX JavaScript where a malformed HTTP response received by ngx.fetch() can crash an NGINX worker when trusted JavaScript reads Response.statusText. Exploitation requires control or influence over the fetched HTTP response.

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Detection Guidance

Detecting this vulnerability requires monitoring for crashes in NGINX worker processes caused by malformed HTTP responses processed by ngx.fetch(). Check NGINX error logs for worker process crashes or segmentation faults. Use commands like 'tail -f /var/log/nginx/error.log' to monitor logs in real-time. Additionally, inspect network traffic for unusual HTTP responses targeting NGINX systems using tools like tcpdump or Wireshark.

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Impact Analysis

This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system. There is no control plane exposure; this is a data plane issue only.

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Compliance Impact

This vulnerability causes a denial-of-service (DoS) on the NGINX system by crashing worker processes when processing malformed HTTP responses. While it does not directly expose control plane data, a DoS condition could disrupt services handling sensitive data, potentially impacting compliance with GDPR (availability requirements) or HIPAA (service continuity for protected health information).

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Mitigation Strategies

Immediately update NGINX to the latest patched version that addresses this issue. If updating is not immediately possible, disable the ngx.fetch() function in JavaScript configurations to prevent exploitation. Restrict network access to NGINX systems to trusted sources only and monitor for unusual traffic patterns.

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