CVE-2026-56387
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk20th percentile - higher than 20% of all known CVEs
Summary
The RTMP AMF parser in Apache bRPC accepts AMF string lengths and array counts directly from untrusted input. A remote unauthenticated attacker can send a small AMF payload with an excessive declared long string length or array count, causing excessive memory allocation before the parser rejects the incomplete payload.
Risk Assessment
This can lead to memory exhaustion and denial of service on bRPC servers with RTMP enabled that accept traffic from untrusted clients.
Recommendation
Upgrade bRPC to version 1.18.0 or apply the patch from PR #3353, then adjust amf_max_string_size and amf_max_array_size limits as needed.
Other vulnerabilities in Apache bRPC
See all- CVE-2026-86249Critical
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-2026-78334Critical
Missing authentication in the streaming RPC path of Apache bRPC (version < 1.18.0) allows a remote attacker to bypass server authentication and inject or deliver streaming frames when a server is configured with an Authenticator. Streaming frames never pass through the authentication hook, and streams can be impersonated by another socket carrying the same id.
- CVE-2026-56388Critical
The Redis server command parser in Apache bRPC accepts an empty RESP array as a command header. A remote unauthenticated attacker can send an empty array header followed by a bulk string, causing an out-of-bounds write in the parser and crashing the process.
- CVE-2026-48830Critical
Improper authentication in Apache bRPC through 1.17.0 allows a remote unauthenticated attacker to bypass authentication for protected builtin HTTP endpoints by first sending a builtin HTTP request on the same HTTP/1.1 keep-alive connection. When ServerOptions.auth is enabled and builtin HTTP services are publicly exposed, the first builtin request may mark the connection as authenticated for later requests.
- 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-2023-31039Critical
Apache bRPC < 1.5.0 on all platforms allows attackers to execute arbitrary code via the ServerOptions::pid_file parameter. An attacker who can influence this parameter when starting the bRPC server can execute arbitrary code with the permissions of the bRPC process.
- CVE-2026-90484Medium
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-2026-87849Medium
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-2026-86147High
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-2026-86146High
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.
Original NVD description (English source)
The RTMP AMF parser in Apache bRPC accepts AMF string lengths and array counts directly from untrusted input. A remote unauthenticated attacker who can reach a bRPC server with RTMP enabled can send a small AMF payload with an excessive declared long string length or array count, causing excessive memory allocation or resource consumption before the parser rejects the incomplete payload. Root Cause: The AMF long string parser resized the destination string to the declared 32-bit length before validating that the stream contained that many bytes. ECMA array and strict array parsers also accepted 32-bit element counts without a configurable upper bound. Affected Scenarios: Deployments that enable the bRPC RTMP server component and accept RTMP traffic from untrusted clients. Direct uses of the AMF parser on untrusted data are also affected. How to Fix: 1. Upgrade bRPC to version 1.18.0, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3353 Note: The fix introduces configurable AMF parsing limits. The default maximum string size is 64 MiB and the default maximum array element count is 1,048,576. Payloads above these limits are rejected. The limits can be adjusted with amf_max_string_size and amf_max_array_size.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

