The Solana Foundation has revealed a security vulnerability in its privacy-focused token system that could have allowed attackers to create fraudulent zero-knowledge proofs, enabling unauthorized minting or withdrawals of tokens. The...
The Solana Foundation has revealed a security vulnerability in its privacy-focused token system that could have allowed attackers to create fraudulent zero-knowledge proofs, enabling unauthorized minting or withdrawals of tokens.
The vulnerability was reported on April 16 through Anza’s GitHub security advisory, along with a proof-of-concept. Engineers from Solana development teams Anza, Firedancer, and Jito confirmed the bug and immediately started working on a solution, as detailed in a post-mortem published on Saturday.
The issue originated from the ZK ElGamal Proof program, which validates zero-knowledge proofs (ZKPs) used in Solana’s Token-22 confidential transfers. These extension tokens secure private balances and transfers by encrypting amounts and using cryptographic proofs for validation.
ZKPs are a cryptographic technique that allows someone to prove knowledge or access to something, like a password or age, without disclosing the information itself. In cryptocurrency applications, they can demonstrate a transaction’s validity without revealing specific amounts or addresses, which can be exploited by malicious actors.
The bug occurred due to missing algebraic components in the hashing process during the Fiat-Shamir transformation, a method to make zero-knowledge proofs non-interactive. A sophisticated attacker could create invalid proofs that the on-chain verifier would accept.
This vulnerability could have enabled unauthorized actions such as unlimited token minting or withdrawals from other accounts. However, standard SPL tokens or the main Token-2022 program logic were unaffected.
Patches were privately distributed to validator operators starting on April 17, with a second patch released later that day to address another related issue in the code. Third-party security firms, including Asymmetric Research, Neodyme, and OtterSec, reviewed both patches. By April 18, a supermajority of validators had implemented the fix.
There is no evidence that the bug was exploited, and all funds remain secure, according to the post-mortem.
