SB2021061730 - Ubuntu update for nettle
Published: June 17, 2021
Security Bulletin ID
SB2021061730
Severity
Medium
Patch available
YES
Number of vulnerabilities
2
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 secuirty vulnerabilities.
1) Cache Attacks (CVE-ID: CVE-2018-16869)
The vulnerability allows a remote attacker to perform a downgrade attack on the server and decrypt private keys on the target system.The vulnerability exists due to a core weakness in TLS that relates to the handshaking of the session key which is used within the tunnel during parallelisation of thousands of oracle queries that occurs using a cluster of TLS servers which share the same public key certificate. A remote attacker can mount a microarchitectural side channel attack against a vulnerable implementation, obtain a network man-in-the-middle position, obtain the relevant data to sign and trigger the victim server to decrypt ciphertexts chosen by the adversary to perform a downgrade attack.
2) Input validation error (CVE-ID: CVE-2021-3580)
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists in nettle's RSA decryption functions due to insufficient validation of certain ciphertexts. A remote attacker can send specially crafted data to the server and perform a denial of service (DoS) attack.
Remediation
Install update from vendor's website.