There are 2 open security issues in buster.
2 issues left for the package maintainer to handle:
Bouncy Castle BC Java before 1.66, BC C# .NET before 1.8.7, BC-FJA before 220.127.116.11, 18.104.22.168, and BC-FNA before 22.214.171.124 have a timing issue within the EC math library that can expose information about the private key when an attacker is able to observe timing information for the generation of multiple deterministic ECDSA signatures.
In Legion of the Bouncy Castle BC before 1.61 and BC-FJA before 126.96.36.199, attackers can obtain sensitive information about a private exponent because of Observable Differences in Behavior to Error Inputs. This occurs in org.bouncycastle.crypto.encodings.OAEPEncoding. Sending invalid ciphertext that decrypts to a short payload in the OAEP Decoder could result in the throwing of an early exception, potentially leaking some information about the private exponent of the RSA private key performing the encryption.
You can find information about how to handle these issues in the security team's documentation.