# CVE-2026-87849: Apache bRPC: Out-of-bounds read via non-object fields in Discovery naming-service reply parsing


- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 21 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-xg38-r433-2m2c

## What is CVE-2026-87849?

CVE-2026-87849 is a medium-severity vulnerability in Apache bRPC, published on 21 Oct 2026. 

### Official description

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 those values are objects. A malformed Discovery response whose data/service members or instances list contain non-object entries (e.g. a bare integer) triggers the RapidJSON object-access precondition on the client, reading memory out of bounds and potentially crashing the bRPC client.

Root Cause:
In src/brpc/policy/discovery_naming_service.cpp, DiscoveryNamingService::GetServers() and DiscoveryNames::ListDiscoveryNodes() access JSON values with member functions on non-object values. RapidJSON only defines these operations for object types; invoking them on a non-object violates the class invariant and results in undefined behavior (out-of-bounds read), commonly crashing the process.

Affected Scenarios: 
An operator-configured (or compromised) Discovery backend returns a malformed /discovery/nodes or /discovery/fetchs response whose data/service/instance entries are not JSON objects, crashing any bRPC client that refreshes its server list.

How to Fix:
1. Upgrade bRPC to version 1.18.0 or later, which fixes this issue.
2. Apply this patch: https://github.com/apache/brpc/pull/3533

The fix validates that the Discovery response data, per-service data, and instance entries are JSON objects (and skips non-object node/instance entries and rejects non-object data/service values) before calling member accessors.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-87849?


## How do I fix CVE-2026-87849?

No fix has been published for CVE-2026-87849 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-87849 being exploited?

There is no known exploitation of CVE-2026-87849 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87849 and fix it if it is affected.

What it is: CVE-2026-87849 is a medium-severity vulnerability in Apache bRPC, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-87849 in the wild and no public exploit code.

Affected product: Apache bRPC. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-87849/ (Markdown: https://insights.sbomify.com/CVE-2026-87849/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87849
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87849
- OSV: https://osv.dev/vulnerability/CVE-2026-87849

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-87849/
Summaries are generated and may contain mistakes; the official description above is the record.