CVE-2026-81755
Low risk· EPSS 13%Exploitation Probability (EPSS)
Low risk13th percentile - higher than 13% of all known CVEs
Summary
A vulnerability in the streaming RPC component of Apache bRPC (versions < 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. The server creates one response stream per stream identifier in the extra_stream_ids field without limiting the number of streams accepted in a single RPC, and each stream allocates its own bthread execution queue and resources.
Risk Assessment
An attacker can exhaust the memory of a bRPC server serving streaming RPC with a single request and make the service unavailable to all clients. The risk affects any bRPC deployment that accepts streams from untrusted clients.
Recommendation
Upgrade Apache bRPC to version 1.18.0 or apply the patch from PR #3493. After upgrading, review the new stream_max_streams_per_request gflag (default 64) and raise it only for applications that legitimately need more than 64 streams per RPC.
Other vulnerabilities in Apache bRPC
See all- CVE-2025-60021Critical
Remote command injection vulnerability in heap profiler builtin service in Apache bRPC (all versions < 1.15.0) on all platforms allows attacker to inject remote command. Root Cause: The bRPC heap profiler built-in service (/pprof/heap) does not validate the user-provided extra_options parameter and executes it as a command-line argument. Attackers can execute remote commands using the extra_options parameter. Affected scenarios: Use the built-in bRPC heap profiler service to perform jemalloc memory profiling. How to Fix: we provide two methods, you can choose one of them: 1. Upgrade bRPC to version 1.15.0. 2. Apply this patch ( https://github.com/apache/brpc/pull/3101 ) manually.
- CVE-2026-90484Low risk· EPSS 4%
The MySQL client response parser in Apache bRPC dereferences a null pointer when the server peer sends a zero-payload-length response packet. A packet with declared zero payload length passes the frame-length check, after which the parser reads the response type byte via an unbounded 5-byte fetch that returns nullptr, causing type = p[4] to dereference it and crash the client process.
- CVE-2026-87849Low risk· EPSS 5%
A vulnerability in the Discovery naming-service reply parser in Apache bRPC (versions < 1.18.0) calls RapidJSON object-only accessors (FindMember) on JSON values without first validating that they are objects. A malformed Discovery response whose data/service members or instances list contain non-object entries triggers an out-of-bounds read and potentially crashes the bRPC client.
- CVE-2026-86249Low risk· EPSS 24%
On a brpc::Server that sets both ServerOptions.auth and ServerOptions.internal_port, the HTTP built-in service exemption on internal_port can be abused to bypass authentication entirely. Verification runs only for the first message of a connection and the result latches the connection, so a request such as GET /status to internal_port authenticates the whole connection.
- CVE-2026-86147Low risk· EPSS 10%
Apache bRPC versions before 1.18.0 expose builtin /flags and /pprof services that allow a remote attacker to change dump paths (bvar_dump_file, bvar_dump_tabs, mbvar_dump_file) and create directories or overwrite files with the server process privileges. Additionally, the ?seconds= parameter in /pprof is not clamped, enabling an attacker to hold the process-wide CPU profiler for an arbitrarily long time.
- CVE-2026-86146Low risk· EPSS 10%
HTTP request/response smuggling vulnerability in Apache bRPC versions < 1.18.0 stems from inconsistent HTTP/1.1 header parsing in its bundled parser. bRPC accepts malformed header forms (space before colon, spaces in Content-Length values, obs-fold, chunked trailers merged as headers, Transfer-Encoding lists with whitespace), allowing attackers to smuggle requests or headers when bRPC is deployed behind a proxy or load balancer.
- CVE-2026-84748Low risk· EPSS 7%
Improper authorization in Apache bRPC (versions < 1.18.0) allows remote attackers to access builtin services through the public port. Protobuf-based protocol dispatch paths computed but did not enforce the security_mode flag, allowing invocation of services such as brpc.vars or hotspots.
- CVE-2026-84747Low risk· EPSS 11%
A vulnerability in Apache bRPC (versions < 1.18.0) stems from an interpretation conflict in HTTP path handling between bRPC and a front proxy. The FindMethodPropertyByURI() function skips empty path segments (consecutive slashes), so paths like //flags are dispatched as /flags, even though RFC 3986 treats them as distinct. Additionally, HTTP/2 does not validate the :path pseudo-header, allowing bypass of proxy ACL rules and access to internal services.
- CVE-2026-84727Medium
A use-after-free exists in the RTMP protocol implementation in Apache bRPC (version < 1.18.0). A malicious RTMP peer can crash the process or potentially corrupt memory via a crafted Abort message. The root cause is that the receive path deletes the target RtmpChunkStream object while the send path concurrently dereferences it without synchronization.
- CVE-2026-82953Low risk· EPSS 12%
A NULL pointer dereference in the RTMP protocol implementation in Apache bRPC (versions < 1.18.0) occurs when the server rejects a createStream request by returning a null stream and then fails to write the error response, causing a crash. A remote attacker can trigger a denial of service by sending a crafted createStream command and closing the connection before the rejection response is written.
Original NVD description (English source)
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) 1. Upgrade bRPC to the 1.18.0 version. 2. Apply this patch: https://github.com/apache/brpc/pull/3493 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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

