CVE-2016-0777

What it actually does

The resend_bytes function in roaming_common.c allows a remote SSH server to request transmission of an entire client buffer, exposing sensitive process memory contents such as private keys.

Why it matters to the business

Organizations risk exposure of authentication credentials and keys when clients connect to untrusted servers, potentially enabling account compromise and downstream breaches; the issue has been public for over a decade with stable exploitability signals.

How an attack unfolds

An attacker hosts or compromises an SSH server configured to trigger the roaming resend mechanism during key exchange; when a vulnerable client connects, the server requests the full buffer, reading private key material and other memory from the client process.

How to fix it

Upgrade OpenSSH clients to version 7.1p2 or later; disable the roaming feature via configuration options in unpatched versions where feasible.

How to confirm the fix worked

Verify client OpenSSH version is 7.1p2 or newer; perform connection tests against controlled servers and inspect memory disclosure behavior.

Typical attack path

1. Attacker positions a malicious or compromised SSH server reachable by targets
2. Victim client initiates an SSH connection to the server
3. Server exploits the roaming resend_bytes path to request oversized buffer transmission
4. Client memory contents including private keys are sent to the attacker

How to detect it

Review SSH client logs for connections to unknown servers and any roaming-related activity indicators; examine process memory artifacts or network captures showing unexpected buffer transmissions.

What your security team should do

• Prioritize patching all OpenSSH client installations across endpoints and servers
• Restrict SSH connections to trusted servers only via allowlists
• Audit and disable roaming support in legacy deployments