CVE-2021-43398: Cryptopp Crypto++

Medium severity, CVSS 5.3. EPSS: 2% chance of exploitation in the next 30 days.

Crypto++ (aka Cryptopp) 8.6.0 and earlier contains a timing leakage in MakePublicKey(). There is a clear correlation between execution time and private key length, which may cause disclosure of the length information of the private key. This might allow attackers to conduct timing attacks. NOTE: this report is disputed by the vendor and multiple third parties. The execution-time differences are intentional. A user may make a choice of a longer key as a tradeoff between strength and performance. In making this choice, the amount of information leaked to an adversary is of infinitesimal value

Affected products

• Cryptopp Crypto++: up to and including 8.6.0

Published 2021-11-04. Last modified 2026-06-17.