CVE-2026-87849: Out-of-bounds Read

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.

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Weakness Type (CWE)

CWE-125 Out-of-bounds Read

References

Other References

https://github.com/apache/brpc/pull/3533 https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb

Frequently Asked Questions

What is CVE-2026-87849? +

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.

How do I check if I'm vulnerable to CVE-2026-87849? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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