Uncontrolled recursion in the AMF parser in Apache bRPC < 1.18.0 allows a remote RTMP peer to crash a bRPC process by sending deeply nested AMF objects or arrays. The parser recursively processed nested AMF containers without enforcing a depth limit, which could exhaust the native stack.
Affected Scenarios:
Applications using bRPC RTMP support and parsing AMF data from an untrusted RTMP peer. This includes RTMP servers parsing client command messages, RTMP clients parsing server responses or status messages, and either side parsing inbound AMF script data such as metadata or cue points. Direct callers of ReadAMFObject or ReadAMFArray on untrusted input are also affected.
How to Fix:
1. Upgrade Apache bRPC to 1.18.0.
2. Apply the patch from PR https://github.com/apache/brpc/pull/3344 .
Note:
The fix introduces a configurable AMF nesting depth limit with default value 128. AMF objects or arrays deeper than amf_max_depth are rejected after applying the fix.