Live › vulnerability › CVE-2026-81755
Go to dashboardA single RPC request can declare a huge number of extra stream identifiers, and the server's StreamAccept creates a response stream and bthread execution queue for each one. An unauthenticated remote client can exhaust server memory and cause denial of service.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Servers built on Apache bRPC that serve streaming RPC and call StreamAccept on streams from untrusted clients are exposed. Services that do not use streaming RPC, or that only accept streams from trusted peers, can skip it.
No product ranges from the sources yet.
grep -ri brpc in the build files or by inspecting the linked library version.StreamAccept for streams from untrusted clients.1.18.0 or later.stream_max_streams_per_request gflag (default 64); raise it only if legitimate requests need more streams per RPC.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
Uncontrolled resource consumption in the streaming RPC component of Apache bRPC (version < 1.18.0) allows a remote attacker to exhaust server memory and cause denial of service by sending a single RPC request that declares an excessive number of streams.
Root Cause:
In the streaming RPC feature, a client can declare multiple streams in one RPC request by putting extra stream identifiers into the repeated field stream_settings.extra_stream_ids of the RPC meta. On the server side, StreamAccept creates one response stream for every stream identifier declared by the request, without limiting the number of streams accepted in a single RPC. The request body size is only bounded by max_body_size (default 64MB), which is enough to carry millions of stream identifiers. Each accepted stream allocates its own bthread execution queue and associated resources, so a single crafted request can make the server create a huge number of streams and exhaust memory, leading to denial of service.
Affected Scenarios:
Use a bRPC server that serves streaming RPC and calls StreamAccept to accept streams from untrusted clients.
How to Fix: (Choose one of the following options)
Note:
The fix adds a new gflag stream_max_streams_per_request with a default value of 64. Requests declaring more streams than the limit are rejected before any response stream is created. Applications that legitimately need to accept more than 64 streams in one RPC must raise this flag; otherwise such requests will fail after applying the fix.
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