SillyTavern Denial of Service via Large JSON Payloads

Executive Summary

This is a denial of service vulnerability in SillyTavern versions 1.12.13 through 1.19.0. It occurs because the body-parser middleware processes incoming requests before authentication and whitelist checks. Attackers can send large or compressed JSON or URL-encoded payloads up to 500 MB, optionally in parallel, to exhaust server memory and CPU resources.

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Detection Guidance

Monitor for unusually large incoming requests or high memory/CPU usage on your SillyTavern server. Check server logs for requests exceeding typical payload sizes. Use network monitoring tools like Wireshark or tcpdump to inspect request sizes and patterns.

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Impact Analysis

This vulnerability allows unauthenticated remote attackers to crash or severely degrade the performance of a SillyTavern server by consuming all available memory and CPU. This can make the service unavailable to legitimate users, disrupting operations for anyone relying on it.

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Compliance Impact

This vulnerability could impact compliance with GDPR and HIPAA by enabling denial-of-service attacks that disrupt service availability. GDPR requires data processing systems to ensure availability and resilience, while HIPAA mandates safeguards against unauthorized resource exhaustion that could compromise protected health information access. The vulnerability's ability to exhaust server resources may violate these standards by impairing system functionality.

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Mitigation Strategies

Upgrade SillyTavern to a version beyond 1.19.0 where the issue is fixed. Alternatively, reduce the global body parser limit to 1 MB in the server configuration and ensure access control middleware runs before body parsing.

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