The Logjam vulnerability is a security flaw that affects the way encrypted connections are established over the internet. It allows attackers to downgrade secure connections to weaker encryption methods, making it easier for them to intercept and read sensitive data. This vulnerability primarily targets the Diffie-Hellman key exchange, which is used in many secure protocols like TLS. To exploit the Logjam vulnerability, an attacker can manipulate the connection between a client and a server, forcing them to use a weaker encryption key. This can lead to unauthorized access to confidential information, such as passwords and personal data. Organizations are encouraged to update their systems and use stronger encryption methods to mitigate this risk.