---
id: "CVE-2026-56388"
kind: "vulnerability"
aliases: ["CVE-2026-56388"]
title: "Apache bRPC: empty Redis array header causes out-of-bounds write and crash"
severity: "high"
cvss: null
epss: 0.00289
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["apache-brpc", "c++", "package", "self-hosted"]
not_affected_if: ["default-config", "redis-service-disabled"]
published_at: "2026-10-21T12:17:21+00:00"
first_seen_at: "2026-10-23T21:57:28+00:00"
updated_at: "2026-10-25T05:02:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56388", "first_seen_at": "2026-10-23T21:57:28+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-56388", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# Apache bRPC: empty Redis array header causes out-of-bounds write and crash

A malformed Redis command with an empty RESP array header makes the bRPC parser write past an empty argument vector. An unauthenticated remote client can crash the server process.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether `ServerOptions.redis_service` is set in your bRPC server code.
- Check the bRPC version with the package manager or build files; affected builds are below `1.18.0`.

## Fix

- Upgrade Apache bRPC to `1.18.0`.
- Or apply the patch from https://github.com/apache/brpc/pull/3354 if you cannot upgrade yet.

## Timeline

- 2026-10-23T21:57:28+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-56388
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-56388

## From the sources

The Redis server command parser in Apache bRPC accepts an empty RESP array as a command header. A remote unauthenticated attacker who can reach a bRPC server with Redis service enabled can send an empty array header followed by a bulk string, causing an out-of-bounds write in the parser and crashing the process.

Root Cause:
RedisCommandParser::ConsumeImpl rejected negative RESP array counts but accepted zero. It resized the command argument vector to zero elements and continued parsing. When a following bulk string was parsed, the only index guard was a CHECK. In configurations where fatal logs do not abort immediately, execution could continue and write to _args[0] even though the vector was empty.

Affected Scenarios:
Deployments that enable ServerOptions.redis_service and accept Redis protocol traffic from untrusted clients. The issue is reached during parsing before command handling or authentication.

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/3354 

Note:
The fix rejects empty RESP arrays as invalid Redis commands and replaces the internal index CHECK with an explicit parse error so malformed command streams cannot fall through to an indexed vector write.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_