fix: add DoS protection for UTXO deserialization#94
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Add configurable script size validation to prevent memory exhaustion attacks in UTXO deserialization functions. The vulnerability existed in NewUTXOFromReader() and NewUTXOValueFromReader() where malicious actors could provide extremely large script length values (up to 4.3GB) causing OOM crashes. The fix validates script lengths against the configurable maxscriptsizepolicy setting (default 500KB) before allocation. Changes: - Add maxUTXOScriptSize variable loaded from settings.Policy - Validate script length before memory allocation in both reader functions - Add comprehensive DoS protection tests including concurrent attack simulation - Add overflow protection capping at math.MaxUint32 Fixes #4248
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🤖 Claude Code Review Status: Complete Summary: No critical issues found. The DoS protection implementation is well-designed and properly addresses the vulnerability. Previously Fixed:
Implementation Quality:
The fix effectively prevents memory exhaustion attacks while maintaining compatibility with BSV's post-Genesis unbounded script sizes through policy-based limits. |
icellan
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Nov 3, 2025
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icellan
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Nov 3, 2025
oskarszoon
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Nov 11, 2025
This reverts commit 3e3412e.
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Summary
Fixes a critical DoS vulnerability in UTXO deserialization where malicious actors could provide extremely large script length values causing memory exhaustion.
Changes
maxUTXOScriptSizevariable loaded fromsettings.Policy.MaxScriptSizePolicy(default 500KB)NewUTXOFromReader()andNewUTXOValueFromReader()math.MaxUint32Vulnerability Details
The vulnerability existed in:
services/utxopersister/UTXO.go:336-NewUTXOFromReader()services/utxopersister/UTXO.go:357-NewUTXOValueFromReader()Both functions read a 4-byte script length from untrusted input and immediately allocate memory without bounds checking. An attacker could provide a script length up to 4.3GB (max uint32), causing OOM crashes.
Security Impact
Before: Attacker could crash Teranode by providing malicious UTXO files/streams with 4.3GB script lengths
After: Script lengths validated against policy limit (default 500KB) before allocation, preventing memory exhaustion
Test Coverage
Configuration
The limit is configurable via
maxscriptsizepolicyin settings:Closes #4248