KubeEdge: Unbounded allocation in viaduct packer enables authenticated remote DoS against CloudHub

Summary

KubeEdge CloudHub uses the viaduct packer to decode messages received from connected peers. The packer reads a 32-bit payload length from the message header and previously allocated a buffer of that size without enforcing an upper bound.

An authenticated peer that can establish a viaduct connection to CloudHub can send a crafted message header containing an excessively large payload length. This may cause CloudHub to allocate a large amount of memory and can result in memory exhaustion, process termination, or denial of service.

Impact

A successfully authenticated malicious or compromised edge node may repeatedly send crafted viaduct message headers to increase CloudHub memory consumption.

Depending on available memory and deployment limits, exploitation may cause:

• Increased CloudHub memory usage
• Out-of-memory termination
• CloudHub restart loops
• Temporary disruption of cloud-edge communication

Authentication to the viaduct endpoint is required. This issue does not provide unauthenticated access or direct code execution.

Root cause

The viaduct packer trusted the payload length encoded in the message header and allocated the payload buffer before validating whether the declared length was within an acceptable range.

Fix

The fix introduces a maximum viaduct payload size of 32 MiB.

The updated implementation:

• Rejects oversized payload lengths in the reader before memory allocation
• Enforces the same maximum size in the writer
• Adds regression tests covering oversized and valid payloads

Fixes have been prepared for the following patch releases:

• KubeEdge v1.23.1
• KubeEdge v1.22.2
• KubeEdge v1.21.2

These versions should not be listed as released until the coordinated release process is complete.

Workarounds

Before patched versions are available, operators should:

• Restrict access to the CloudHub endpoint to trusted edge nodes and networks
• Protect and rotate edge-node credentials
• Revoke credentials belonging to decommissioned or potentially compromised nodes
• Apply memory limits and restart policies to the CloudHub workload
• Monitor CloudHub memory consumption and unexpected connection activity

Affected component

• pkg/viaduct/pkg/packer
• CloudHub viaduct message-processing path

Credits

KubeEdge thanks Sang-Hoon Choi (, Sejong University) for responsibly reporting this issue and for coordinating with the KubeEdge maintainers through the security disclosure process.