Heap Buffer Overflow in libsoup Due to Unlimited Payload Size

Executive Summary

This is a heap buffer overflow vulnerability in libsoup, a library for HTTP and WebSocket communication. When the max-incoming-payload-size is set to unlimited (0), an attacker can send a very large WebSocket frame that causes the incoming buffer to grow beyond its allocated size. This leads to heap corruption or denial of service by writing past the buffer's memory.

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Detection Guidance

Check if libsoup is installed and its version using commands like 'rpm -q libsoup' or 'dpkg -l libsoup'. Monitor WebSocket traffic for unusually large payloads or crashes in applications using libsoup. Inspect logs for heap corruption errors or application segmentation faults.

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Impact Analysis

An attacker could exploit this to read sensitive memory such as cryptographic keys or personal data, bypass security mechanisms like ASLR, or crash the application causing a denial of service. The impact depends on the application's use of libsoup and whether payload size limits are disabled.

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Mitigation Strategies

Set a finite max-incoming-payload-size in libsoup configurations to prevent unlimited buffer growth. Restrict WebSocket connections to trusted peers only. Upgrade libsoup to version 3.7.3 or later if available. Apply vendor patches or mitigations as recommended by Red Hat or other vendors.

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