Executive brief
Apple's container port forwarding service allows remote attackers to exhaust memory on the host system by sending data to a published TCP port before the container application is ready to accept the connection. An attacker can force the forwarding process to buffer unlimited amounts of client data in memory indefinitely, potentially causing the host system to run out of memory and crash, disrupting all running containers.
Technical details
The vulnerability exists in the ConnectHandler component of the TCP port forwarder in Apple's container, introduced when TCP/UDP port forwarding was first added in version 0.3.0. The forwarder buffers client data sent before the backend container connection is accepted, with no limits on buffer size or duration. An unauthenticated network attacker who can reach a container's published TCP port can repeatedly send data and keep connections open, forcing unbounded memory consumption on the host's container-runtime-linux process. The UDP forwarder uses a separate bounded queue and is not affected. The vulnerability is patched in version 1.2.0; affected versions are 0.3.0 through 1.1.0. Mitigation prior to patching includes binding published ports to localhost (127.0.0.1) or ensuring the backend application accepts connections promptly.
Affected products
- Apple container 0.3.0 to 1.1.0
Timeline
- 2026-08-12: disclosed
- 2026-08-20: advisory
- 2026-08-20: patched: Version 1.2.0 released