Headline
GHSA-g3qg-6746-3mg9: zkVM Underconstrained Vulnerability
Due to a missing constraint in the rv32im circuit, any 3-register RISC-V instruction (including remu and divu) in risc0-zkvm 2.0.0, 2.0.1, and 2.0.2 are vulnerable to an attack by a malicious prover. The main idea for the attack is to confuse the RISC-V virtual machine into treating the value of the rs1 register as the same as the rs2 register due to a lack of constraints in the rv32im circuit.
This vulnerability was reported by Christoph Hochrainer via our Hackenproof bug bounty.
The fix for the circuit was implemented in zirgen/pull/238, and the update to risc0 was implemented in risc0/pull/3181. Impacted on-chain verifiers have already been disabled via the estop mechanism outlined in the Verifier Management Design.
Mitigation
It is recommend all impacted users upgrade as soon as possible.
Rust applications using the risc0-zkvm crate at versions 2.0.0, 2.0.1, and 2.0.2 should upgrade to version 2.1.0.
Smart contract applications using the official RISC Zero Verifier Router do not need to take any action: zkVM version 2.1 is active on all official routers, and version 2.0 has been disabled.
Smart contract applications not using the verifier router should update their contracts to send verification calls to the 2.1 version of the verifier.
- GitHub Advisory Database
- GitHub Reviewed
- CVE-2025-52484
zkVM Underconstrained Vulnerability
Low severity GitHub Reviewed Published Jun 18, 2025 in risc0/risc0 • Updated Jun 20, 2025
Package
cargo risc0-circuit-rv32im (Rust)
Affected versions
>= 2.0.0, <= 2.0.3
Due to a missing constraint in the rv32im circuit, any 3-register RISC-V instruction (including remu and divu) in risc0-zkvm 2.0.0, 2.0.1, and 2.0.2 are vulnerable to an attack by a malicious prover. The main idea for the attack is to confuse the RISC-V virtual machine into treating the value of the rs1 register as the same as the rs2 register due to a lack of constraints in the rv32im circuit.
This vulnerability was reported by Christoph Hochrainer via our Hackenproof bug bounty.
The fix for the circuit was implemented in zirgen/pull/238, and the update to risc0 was implemented in risc0/pull/3181. Impacted on-chain verifiers have already been disabled via the estop mechanism outlined in the Verifier Management Design.
Mitigation
It is recommend all impacted users upgrade as soon as possible.
Rust applications using the risc0-zkvm crate at versions 2.0.0, 2.0.1, and 2.0.2 should upgrade to version 2.1.0.
Smart contract applications using the official RISC Zero Verifier Router do not need to take any action: zkVM version 2.1 is active on all official routers, and version 2.0 has been disabled.
Smart contract applications not using the verifier router should update their contracts to send verification calls to the 2.1 version of the verifier.
References
- GHSA-g3qg-6746-3mg9
- risc0/risc0#3181
- risc0/zirgen#238
- https://nvd.nist.gov/vuln/detail/CVE-2025-52484
- risc0/risc0@006d86c
- risc0/risc0@1873bbb
- risc0/risc0@67f2d81
- risc0/zirgen@e0e2918
Published to the GitHub Advisory Database
Jun 20, 2025
Last updated
Jun 20, 2025