Unbounded HTTP response body read in OpenTelemetry.Resources.Azure

Summary

OpenTelemetry.Resources.Azure is the .NET resource detector for Azure environments. In versions 1.15.0-beta.1 and earlier, the AzureVmMetaDataRequestor class makes HTTP requests to the Azure VM instance metadata service and reads the response body into memory without any size limit. An attacker who controls the configured endpoint, or who can intercept traffic to it via a man-in-the-middle attack, can return an arbitrarily large response body. This causes unbounded heap allocation in the consuming process, leading to high transient memory pressure, garbage-collection stalls, or an OutOfMemoryException that terminates the process. As a workaround, disable the Azure VM resource detector or use network-level controls such as firewall rules, mTLS, or a service mesh to prevent man-in-the-middle attacks on the Azure VM instance metadata endpoint. This issue is fixed in version 1.15.1-beta.1, which streams responses rather than buffering them entirely in memory and ignores responses larger than 4 MiB.