7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
0.001 Low
EPSS
Percentile
46.9%
Frontier’s modexp
precompile uses num-bigint
crate under the hood. In the implementation, 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
is currently available, and thus this advisory will be first 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.
The short-term fix for Frontier is deployed at PR 1017.
The recommendations are as follows:
None.
A similar issue was presented in Geth’s implementation and the fix can be found here.
github.com/advisories/GHSA-fcmm-54jp-7vf6
github.com/paritytech/frontier/commit/5af12e94d7dfc8a0208a290643a800f55de7b219
github.com/paritytech/frontier/pull/1017
github.com/paritytech/frontier/security/advisories/GHSA-fcmm-54jp-7vf6
github.com/rust-num/num-bigint/blob/6f2b8e0fc218dbd0f49bebb8db2d1a771fe6bafa/src/biguint/power.rs#L134
nvd.nist.gov/vuln/detail/CVE-2023-28431