{"id":"CVE-2021-38194","aliases":["EUVD-2021-1846","GHSA-qj3v-q2vj-4c8h","RUSTSEC-2021-0075"],"status":"published","title":"Calculation error in ark-r1cs-std","description":"An issue was discovered in the ark-r1cs-std crate before 0.3.1 for Rust. It does not enforce any constraints in the FieldVar::mul_by_inverse method. Thus, a prover can produce a proof that is unsound but is nonetheless verified.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.01275,"percentile":0.70167,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-682"],"published":"2021-07-08T12:00:00Z","modified":"2026-06-17T04:01:44Z","fixes":[{"ecosystem":"crates.io","package":"ark-r1cs-std","fixed_in":["0.3.1"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"crates.io","package":"ark-r1cs-std","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.2.0"},{"fixed":"0.3.1"}]}]},{"source":"osv","ecosystem":"crates.io","package":"ark-r1cs-std","ranges":[{"type":"SEMVER","events":[{"introduced":"0.2.0"},{"fixed":"0.3.1"}]}]},{"source":"osv","ecosystem":"crates.io","package":"ark-r1cs-std","ranges":[{"type":"SEMVER","events":[{"introduced":"0.0.0-0"},{"fixed":"0.3.1"}]}]}],"products":[{"vendor":"arcworks","product":"ark-r1cs-std"}],"references":[{"url":"https://rustsec.org/advisories/RUSTSEC-2021-0075.html","tags":["x_refsource_MISC","x_transferred","Exploit","Issue Tracking","Patch","Third Party Advisory","web","advisory"]},{"url":"https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/ark-r1cs-std/RUSTSEC-2021-0075.md","tags":["x_refsource_MISC","x_transferred","Third Party Advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-38194","tags":["advisory"]},{"url":"https://github.com/arkworks-rs/r1cs-std/pull/70","tags":["web"]},{"url":"https://github.com/arkworks-rs/r1cs-std/commit/47ddbaa411afe7c499311a248a38135e5a192b67","tags":["web"]},{"url":"https://github.com/advisories/GHSA-qj3v-q2vj-4c8h"},{"url":"https://github.com/arkworks-rs/r1cs-std","tags":["package"]},{"url":"https://crates.io/crates/ark-r1cs-std","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2021-38194","description":"An issue was discovered in the ark-r1cs-std crate before 0.3.1 for Rust. It does not enforce any constraints in the FieldVar::mul_by_inverse method. Thus, a prover can produce a proof that is unsound but is nonetheless verified.","status":"published","published":"2021-08-08T05:08:44Z","modified":"2024-08-04T01:37:16.197Z","updated_at":"2026-11-02T14:33:07.349244Z"}],"euvd":[{"id":"EUVD-2021-1846","description":"An issue was discovered in the ark-r1cs-std crate before 0.3.1 for Rust. It does not enforce any constraints in the FieldVar::mul_by_inverse method. Thus, a prover can produce a proof that is unsound but is nonetheless verified.","status":"published","published":"2021-08-08T05:08:44Z","modified":"2024-08-04T01:37:16Z","updated_at":"2026-11-03T03:24:25.244479Z"}],"ghsa":[{"id":"GHSA-qj3v-q2vj-4c8h","title":"Calculation error in ark-r1cs-std","description":"An issue was discovered in the ark-r1cs-std crate before 0.3.1 for Rust. It does not enforce any constraints in the FieldVar::mul_by_inverse method. Thus, a prover can produce a proof that is unsound but is nonetheless verified.","status":"published","published":"2021-08-25T20:55:58Z","modified":"2023-04-18T14:51:25Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-682"],"updated_at":"2026-11-02T14:36:51.39133Z"}],"nvd":[{"id":"CVE-2021-38194","description":"An issue was discovered in the ark-r1cs-std crate before 0.3.1 for Rust. It does not enforce any constraints in the FieldVar::mul_by_inverse method. Thus, a prover can produce a proof that is unsound but is nonetheless verified.","status":"published","published":"2021-08-08T06:15:09.08Z","modified":"2026-06-17T04:01:44.123Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"},{"version":"2.0","score":7.5,"vector":"AV:N/AC:L/Au:N/C:P/I:P/A:P","level":"high","assessor":"primary"}],"updated_at":"2026-11-02T14:06:56.562207Z"}],"osv":[{"id":"GHSA-qj3v-q2vj-4c8h","title":"Calculation error in ark-r1cs-std","description":"An issue was discovered in the ark-r1cs-std crate before 0.3.1 for Rust. It does not enforce any constraints in the FieldVar::mul_by_inverse method. Thus, a prover can produce a proof that is unsound but is nonetheless verified.","status":"published","published":"2021-08-25T20:55:58Z","modified":"2023-11-08T04:06:26.167178Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-682"],"updated_at":"2026-11-02T15:46:54.760124Z"},{"id":"RUSTSEC-2021-0075","title":"Flaw in `FieldVar::mul_by_inverse` allows unsound R1CS constraint systems","description":"Versions `0.2.0` to `0.3.0` of ark-r1cs-std did not enforce any constraints in the `FieldVar::mul_by_inverse` method, allowing a malicious prover to produce an unsound proof that passes all verifier checks.\nThis method was used primarily in scalar multiplication for [`short_weierstrass::ProjectiveVar`](https://docs.rs/ark-r1cs-std/0.3.0/ark_r1cs_std/groups/curves/short_weierstrass/struct.ProjectiveVar.html).\n\nThis bug was fixed in commit `47ddbaa`, and was released as part of version `0.3.1` on `crates.io`.","status":"published","published":"2021-07-08T12:00:00Z","modified":"2023-11-08T04:06:26.167178Z","updated_at":"2026-11-02T15:53:39.492624Z"}]}}