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CVE-2026-56387— Apache bRPC: Remote Memory Exhaustion in RTMP AMF Parser

Quick assessment

Affected
Apache Software Foundation Apache bRPC
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Apache bRPC 中的 RTMP AMF 解析器会直接从不可信输入中接受 AMF 字符串长度和数组元素数量。任何能够访问启用了 RTMP 功能的 bRPC 服务器的远程未认证攻击者，均可发送一个极小的 AMF 负载，其中声明了过长的字符串长度或过大的数组元素数量。这会导致解析器在拒绝该不完整负载之前，先进行过度的内存分配或资源消耗，从而引发拒绝服务（DoS）风险。 根本原因： AMF 长字符串解析器在验证数据流是否包含相应字节数之前，便根据声明的 32 位长度调整目标字符串的大小。此外，ECMA 数组和严格数

AI Predicted 5.5 Difficulty: Trivial

Possible ATT&CK Techniques 1 AI

T1499.003 · Application Exhaustion Flood
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I. Basic Information for CVE-2026-56387

Vulnerability Information
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Vulnerability Title
Apache bRPC: Remote Memory Exhaustion in RTMP AMF Parser
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
未经控制的内存分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Apache Software Foundation Apache bRPC 0 ~ 1.18.0 -

II. Public POCs for CVE-2026-56387

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III. Intelligence Information for CVE-2026-56387

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Same Patch Batch · Apache Software Foundation · 2026-10-21 · 59 CVEs total

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CVE-2026-105869 9.2 CRITICAL Apache Pulsar: MultiRolesTokenAuthorizationProvider uses roles from unverified tokens for
CVE-2025-31699 8.9 HIGH Apache Traffic Server: Origin connection still owed a request body is reused, enabling req
CVE-2026-105937 8.7 HIGH Apache Pulsar: Missing authorization of the shadow topic source allows cross-tenant messag
CVE-2025-55702 8.7 HIGH Apache Traffic Server: An unread Expect: 100-continue request body is framed as a new requ
CVE-2026-111804 8.2 HIGH Apache Traffic Server: wasm plugin has a use-after-free and forwards unvalidated guest met
CVE-2026-105942 7.7 HIGH Apache Pulsar: Original principal of proxied requests authorized with the proxy's authenti
CVE-2026-105945 7.7 HIGH Apache Pulsar: Improper Validation of Package Name Components Allows Cross-Tenant Package
CVE-2026-105934 7.2 HIGH Apache Pulsar: Missing tenant admin authorization check when truncating a partitioned topi
CVE-2026-105930 6.0 MEDIUM Apache Pulsar: Improper Authorization of Function, Source and Sink Package URLs Allows Cro
CVE-2026-105936 5.3 MEDIUM Apache Pulsar: Functions connectors list endpoint does not apply the super-user check of t
CVE-2026-105926 5.3 MEDIUM Apache Pulsar: Missing Topic Authorization on Binary Protocol GetSchema and GetOrCreateSch
CVE-2026-105935 4.9 MEDIUM Apache Pulsar: Function trigger publishes to the input topic without checking the caller's
CVE-2026-105927 2.3 LOW Apache Pulsar: Improper authorization of WebSocket consumer dead letter topic allows write
CVE-2026-105938 2.3 LOW Apache Pulsar: Subscription authorization policies not enforced by namespace-level backlog
CVE-2026-105932 2.3 LOW Apache Pulsar: Missing topic policy authorization on non-persistent topic entry filter end
CVE-2026-105931 2.3 LOW Apache Pulsar: Missing authorization on transaction admin endpoints exposes transaction co
CVE-2026-105933 2.3 LOW Apache Pulsar: Namespace encryption requirement not enforced after a failure during topic

Showing top 20 of 59 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Apache bRPC
Same vendor: Apache Software Foundation
Same weakness: CWE-789

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