CVE-2016-8610

What it actually does

The flaw allows a remote attacker to send crafted TLS ALERT packets during the handshake, causing the server to enter a tight processing loop that consumes excessive CPU and prevents acceptance of new connections.

Why it matters to the business

Servers become unavailable to legitimate clients until the attack stops or the service is restarted, leading to downtime for any application relying on the affected TLS stack; urgency is low given the CVE's age and lack of active exploitation.

How an attack unfolds

An attacker initiates a TLS connection and injects repeated ALERT records that the server processes without rate limiting, triggering sustained CPU exhaustion on the target process.

How to fix it

Upgrade affected libgit2 packages on Alpine v3.8, v3.10, and v3.11 to version 0.27.3-r0 or later; rebuild any dependent applications against the patched library and restart affected services.

How to confirm the fix worked

Confirm the running libgit2 version is 0.27.3-r0 or newer using package manager queries; perform TLS handshake tests with malformed ALERT packets in a lab environment to verify the loop no longer occurs.

Typical attack path

1. Attacker establishes a TCP connection to the TLS listener
2. Attacker sends a ClientHello followed by multiple crafted ALERT packets
3. Server enters CPU-bound loop while processing the alerts
4. Legitimate clients are denied service until the attack ceases

How to detect it

Look in application and system logs for repeated TLS handshake failures or sustained high CPU on processes that perform TLS; correlate with network flows showing many short-lived connections from single sources.

What your security team should do

• Prioritize patching Alpine-based systems running libgit2 within standard maintenance windows
• Review TLS termination points for exposure to untrusted networks
• Monitor CPU usage on services handling TLS handshakes for anomalous spikes