CVE-2023-33252 in snarkjs
Summary
by MITRE • 05/22/2023
iden3 snarkjs through 0.6.11 allows double spending because there is no validation that the publicSignals length is less than the field modulus.
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Analysis
by VulDB Data Team • 07/14/2025
The vulnerability identified as CVE-2023-33252 affects the iden3 snarkjs library version 0.6.11 and earlier, presenting a critical security risk that enables double spending attacks within zero-knowledge proof systems. This flaw resides in the cryptographic validation mechanisms that govern how public signals are processed during proof generation and verification. The root cause stems from insufficient input validation where the system fails to verify that public signal lengths remain below the field modulus threshold, creating a mathematical vulnerability that adversaries can exploit to manipulate transaction outcomes.
The technical flaw manifests in the cryptographic protocol's handling of public signals within zero-knowledge proofs, specifically when these signals exceed the mathematical boundaries defined by the underlying field modulus. This condition creates a scenario where malicious actors can construct proofs that appear valid to the verification system while actually representing fraudulent transactions. The vulnerability operates at the intersection of number theory and cryptographic security, where the field modulus serves as a critical boundary that ensures mathematical consistency within elliptic curve operations. When this boundary is exceeded, it creates mathematical inconsistencies that can be leveraged to bypass security checks designed to prevent duplicate transactions.
The operational impact of this vulnerability extends beyond simple transaction manipulation to potentially compromise entire blockchain networks that rely on snarkjs for cryptographic verification. Double spending attacks can result in significant financial losses and undermine trust in systems that depend on zero-knowledge proofs for transaction validation. The attack surface is particularly concerning for decentralized applications and privacy-focused blockchain implementations where snarkjs is commonly deployed. This vulnerability affects the fundamental integrity of cryptographic proofs and can lead to cascading failures in systems where multiple transactions depend on the same proof verification mechanisms.
Mitigation strategies for CVE-2023-33252 require immediate implementation of proper input validation checks that enforce public signal length constraints against the field modulus. Organizations should upgrade to snarkjs version 0.6.12 or later where this validation has been implemented. Security teams must conduct comprehensive audits of all systems using affected versions to identify potential exploitation vectors and implement additional monitoring for anomalous transaction patterns. The fix addresses the underlying CWE-129 vulnerability category related to insufficient validation of length attributes and aligns with ATT&CK techniques targeting cryptographic validation weaknesses. Network defenders should also implement runtime checks that monitor for public signal values approaching or exceeding field modulus boundaries, providing early detection capabilities for potential exploitation attempts.