CVE-2016-3947

What it actually does

Heap-based buffer overflow in the Icmp6::Recv function allows remote servers to trigger memory corruption via crafted ICMPv6 packets, leading to denial of service through performance degradation or transition failures and potential leakage of sensitive information into log files.

Why it matters to the business

Service availability can degrade or fail for environments relying on the affected component, with risk of sensitive operational data appearing in logs that may be accessible to unauthorized viewers; the issue affects a widely used networking utility present in many deployments, increasing exposure surface.

How an attack unfolds

An attacker-controlled remote server crafts and sends a malicious ICMPv6 packet that is processed by the pinger utility's Icmp6::Recv handler, overflowing the heap buffer and causing either service instability or unintended writes of memory contents to logs.

How to fix it

Upgrade the affected component to a fixed release such as flux-source-controller-0 version 0.36.1-r2 or later; apply equivalent patches for Squid 3.5.16 and 4.0.8 or newer where the pinger utility is used.

How to confirm the fix worked

Verify the installed version against the fixed release list, recompile or redeploy with the updated package, and confirm that ICMPv6 handling no longer exhibits buffer overflow behavior through targeted packet tests or memory analysis tools.

Typical attack path

1. Identify a target running the vulnerable pinger component reachable via IPv6
2. Send a specially crafted ICMPv6 packet from a controlled remote server
3. Trigger the buffer overflow in Icmp6::Recv leading to DoS or log leakage
4. Observe service degradation or inspect logs for sensitive data exposure

How to detect it

Review system and application logs for unusual ICMPv6 packet processing entries or abrupt performance changes around the pinger process; correlate with network flow data showing unexpected IPv6 ICMP traffic from external sources.

What your security team should do

• Prioritize immediate upgrade to the specified fixed version across all instances
• Disable or restrict IPv6 ICMP processing if the functionality is not required
• Monitor for any post-upgrade performance or transition issues
• Review log retention policies to limit exposure of any previously leaked data