CVE-2026-80463

Unbounded memory accumulation in the stream message reassembly path of Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to exhaust the memory of a server (denial of service) by sending an endless sequence of continuation data frames.

Root Cause: The streaming RPC protocol bounds every single data frame by max body size, but a fragmented stream message accumulates continuation frames into one buffer ( pending buf) without any limit on the accumulated size. A malicious peer that can open a stream can therefore keep sending continuation frames to make the receiver accumulate an arbitrarily large in-memory message. Since the default flow-control settings (socket max streams unconsumed bytes=0) do not throttle the sending rate, the receiver's memory grows until the process runs out of memory and crashes or becomes unavailable.

Affected Scenarios: Services that accept streams from untrusted clients (for example using brpc::StreamAccept or brpc::StreamCreate with the built-in streaming protocol) are affected.

How to Fix: (Choose one of the following options)

Note: The fix limits the accumulated payload of a fragmented stream message to max body size (default 64MB). When the accumulated payload exceeds the limit, the pending fragments are released and the stream is closed with error EMSGSIZE. After applying the fix, legitimate fragmented stream messages larger than max body size will be rejected; you can adjust the gflag max body size to change the limit.