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CVE-2026-74757— Apache bRPC: Uncontrolled Memory Allocation via Malicious mcpack Array Item Count

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（版本 < 1.18.0）所有平台上的 组件存在资源分配失控漏洞。远程攻击者可通过发送包含巨大数组元素计数的伪造 mcpack 请求，迫使服务器分配大量内存。 根本原因： bRPC 的 解析器在未对实际负载大小进行验证的情况下，直接信任 mcpack 数组头部中存储的元素计数。由 protoc 插件生成的代码利用该计数，通过 方法为重复的 protobuf 字段预分配内存。若攻击者构造一个声明 的畸形请求，可强制服务器预分配约 16GB 虚拟内存，在内存受限的主机上可能导致进程因触发 信号而异

AI Predicted 7.5 Difficulty: Trivial
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I. Basic Information for CVE-2026-74757

Vulnerability Information
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Vulnerability Title
Apache bRPC: Uncontrolled Memory Allocation via Malicious mcpack Array Item Count
Source: CVE Program / CVE List V5
Vulnerability Description
Uncontrolled resource allocation in the mcpack2pb component in Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to make the server allocate a large amount of memory via sending a crafted mcpack request with a huge array item count. Root Cause: The bRPC mcpack2pb parser trusts the item count stored in the mcpack array header without validating it against the actual payload size. The code generated by the mcpack2pb protoc plugin uses this count to preallocate memory for repeated protobuf fields via Reserve(). A malformed request declaring item_count = 0x7fffffff can force the server to preallocate about 16GB of virtual memory, which may abort the process (SIGABRT) on memory-constrained hosts. Affected Scenarios: Use a bRPC server that wires a NsheadService to UbrpcMcpack2Adaptor (the Baidu ubrpc deployment pattern) and parses requests with code generated by the mcpack2pb protoc plugin. The request body is parsed before authentication. How to Fix: (Choose one of the following options) 1. Upgrade bRPC to version 1.18.0, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3451 Note: No matter which option you choose, you should know that the fix caps the array item count to the remaining bytes of the array payload.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
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-2026-74757

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III. Intelligence Information for CVE-2026-74757

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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 &rarr; →

IV. Related Vulnerabilities

Same product: Apache bRPC
Same vendor: Apache Software Foundation
Same weakness: CWE-770

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