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Apache bRPC: Missing authentication for streaming RPC frames

CVE-2026-78334Critical 9.1

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Summary

Apache bRPC before version 1.18.0 does not check authentication for streaming RPC frames. If a server is configured with an Authenticator, a remote attacker without credentials can inject or receive streaming frames and can bind a stream to a foreign connection by its ID. This can lead to unauthorized data changes or delivery and to availability impact. The issue only applies to servers with authentication configured that accept streaming RPC from untrusted networks.

Affected

  • Apache bRPC on all platforms, versions 0 to before 1.18.0
  • Only servers configured with an Authenticator

Fixed in

  • Upgrade to Apache bRPC 1.18.0
  • Alternatively, apply PR #3481 (https://github.com/apache/brpc/pull/3481)

Workaround

  • Ensure that authentication is actively enabled on the server.
  • Do not accept streaming RPC from untrusted networks; restrict access at network level.
  • No other mitigation known.

Exploitation

  • No known exploitation in the wild; no public proof of concept found.
  • CISA SSVC: automatable yes, technical impact total, exploitation none.

Our recommendation

  • Check whether bRPC is used in your products or services and identify versions below 1.18.0.
  • Upgrade to 1.18.0 or apply the fix; patch all bRPC issues of this release together, including CVE-2026-86249 and CVE-2026-48830.
  • Restrict exposure of streaming RPC services to trusted networks.
  • Verify the release date and checksums on the official Apache or GitHub release page before deploying.
  • Re-check the CVSS score on NVD; the score of 9.1 could not be confirmed there.

Public exploits

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 05:37.

Original description (NVD)

Missing authentication in the streaming RPC path of Apache bRPC (version < 1.18.0) on all platforms allows a remote attacker to bypass server authentication and inject or deliver streaming frames, when a server is configured with an Authenticator. Root Cause: When authentication is configured, streaming RPC frames are consumed directly by the streaming parser (ParseStreamingMessage) and never pass through InputMessenger's authentication hook, so an unauthenticated peer can exchange frames without being authenticated. In addition, a server-accepted stream is bound lazily to the first frame that happens to carry its id, so a stream could accept a frame carrying its id from a socket other than the socket that created the stream. Affected Scenarios: A bRPC server configured with authentication that serves streaming RPC from an untrusted network, or a deployment where a foreign connection can impersonate a stream by id, can be made to accept unauthorized streaming frames. How to Fix: Upgrade bRPC to 1.18.0, which fixes this issue, or apply the patch in PR https://github.com/apache/brpc/pull/3481. Note: The fix rejects streaming frames on server sockets when configured authentication has not completed, and keeps server-accepted streams bound to the socket of their creating RPC and rejects frames arriving from another socket. Authenticated streaming RPC behavior and the wire format are unchanged; only unauthenticated or foreign-socket frames are now rejected.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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