CVE-2023-28431
Frontier is an Ethereum compatibility layer for Substrate. Frontier's `modexp` precompile uses `num-bigint` crate under the hood. In the implementation prior to pull request 1017, the cases for modulus being even and modulus being odd are treated separately. Odd modulus uses the fast Montgomery multiplication, and even modulus uses the slow plain power algorithm. This gas cost discrepancy was not accounted for in the `modexp` precompile, leading to possible denial of service attacks.
No fixes for `num-bigint` are currently available, and thus this issue is fixed in the short term by raising the gas costs for even modulus, and in the long term fixing it in `num-bigint` or switching to another modexp implementation.
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The short-term fix for Frontier is deployed at pull request 1017. There are no known workarounds aside from applying the fix.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 7.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.87%
- Percentil entre todas las CVEs puntuadas: 58
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- CWE-682
Referencias
- https://github.com/paritytech/frontier/commit/5af12e94d7dfc8a0208a290643a800f55de7b219
- https://github.com/paritytech/frontier/pull/1017
- https://github.com/paritytech/frontier/security/advisories/GHSA-fcmm-54jp-7vf6
- https://github.com/rust-num/num-bigint/blob/6f2b8e0fc218dbd0f49bebb8db2d1a771fe6bafa/src/biguint/power.rs#L134
- https://github.com/paritytech/frontier/commit/5af12e94d7dfc8a0208a290643a800f55de7b219
- https://github.com/paritytech/frontier/pull/1017
- https://github.com/paritytech/frontier/security/advisories/GHSA-fcmm-54jp-7vf6
- https://github.com/rust-num/num-bigint/blob/6f2b8e0fc218dbd0f49bebb8db2d1a771fe6bafa/src/biguint/power.rs#L134
JSON original (NVD)
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