CVE-2025-52484: Risc0 zkvm ZkVM Underconstrained Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-g3qg-6746-3mg9",
  "modified" : "2025-06-27T23:59:02Z",
  "published" : "2025-06-20T18:08:04Z",
  "aliases" : [ "CVE-2025-52484" ],
  "summary" : "zkVM Underconstrained Vulnerability",
  "details" : "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.\n\nThis vulnerability was reported by Christoph Hochrainer via our Hackenproof bug bounty. We have evaluated the severity of the vulnerability as “Critical,” and paid a bounty. \n\nThe fix for the circuit was implemented in [zirgen/pull/238](https://github.com/risc0/zirgen/pull/238), and the update to risc0 was implemented in [risc0/pull/3181](https://github.com/risc0/risc0/pull/3181). Impacted on-chain verifiers have already been disabled via the estop mechanism outlined in the [Verifier Management Design](https://github.com/risc0/risc0-ethereum/blob/release-2.0/contracts/version-management-design.md#base-verifier-implementations). \n\n## Mitigation\nWe recommend all impacted users upgrade as soon as possible.\n\nRust 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.\n\nSmart contract applications using the official [RISC Zero Verifier Router](https://dev.risczero.com/api/blockchain-integration/contracts/verifier#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.\n\nSmart contract applications not using the verifier router should update their contracts to send verification calls to the 2.1 version of the verifier.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "risc0-zkvm"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.1.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.0.2"
    }
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "risc0-circuit-rv32im"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.0.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.0.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/risc0/risc0/security/advisories/GHSA-g3qg-6746-3mg9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-52484"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/risc0/risc0/pull/3181"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/risc0/zirgen/pull/238"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/risc0/risc0/commit/006d86c363b16d2b2ac42d32d832a209ff8ab4c9"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/risc0/risc0/commit/1873bbb8a56793edd1f6195242d184cf6cc5175d"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/risc0/risc0/commit/67f2d81c638bff5f4fcfe11a084ebb34799b7a89"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/risc0/zirgen/commit/e0e2918302c93e956f73ca2e44aef2b861d8c3ae"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/risc0/risc0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-345" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-06-20T18:08:04Z",
    "nvd_published_at" : "2025-06-20T18:15:28Z"
  }
}