Description
Unbounded memory accumulation in the stream message reassembly path of Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to exhaust the memory of a server (denial of service) by sending an endless sequence of continuation data frames.

Root Cause:
The streaming RPC protocol bounds every single data frame by max_body_size, but a fragmented stream message accumulates continuation frames into one buffer (_pending_buf) without any limit on the accumulated size. A malicious peer that can open a stream can therefore keep sending continuation frames to make the receiver accumulate an arbitrarily large in-memory message. Since the default flow-control settings (socket_max_streams_unconsumed_bytes=0) do not throttle the sending rate, the receiver's memory grows until the process runs out of memory and crashes or becomes unavailable.

Affected Scenarios:
Services that accept streams from untrusted clients (for example using brpc::StreamAccept or brpc::StreamCreate with the built-in streaming protocol) are affected.


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/3489


Note:
The fix limits the accumulated payload of a fragmented stream message to max_body_size (default 64MB). When the accumulated payload exceeds the limit, the pending fragments are released and the stream is closed with error EMSGSIZE. After applying the fix, legitimate fragmented stream messages larger than max_body_size will be rejected; you can adjust the gflag max_body_size to change the limit.
Published: 2026-10-21
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service through memory exhaustion
Action: Immediate Patch
AI Analysis

Impact

Apache bRPC is vulnerable to unbounded memory accumulation during stream message reassembly. When a client sends an endless sequence of continuation frames, the receiver accumulates them in an unbounded buffer, leading to memory exhaustion and eventual process termination. This flaw exploits an improper limits weakness (CWE-770) and results in a denial of service condition that can be triggered over the network.

Affected Systems

The vulnerability affects Apache Software Foundation’s Apache bRPC library version less than 1.18.0 on all supported platforms, wherever services accept streams from untrusted clients using the built‑in streaming protocol such as brpc::StreamAccept or brpc::StreamCreate.

Risk and Exploitability

Attackers can exploit the flaw remotely by opening a stream and sending continuous continuation frames. The default flow‑control settings do not throttle this traffic, allowing the attacker to drive memory usage to catastrophic levels. The CVSS score of 7.5 indicates high severity. The EPSS score of < 1% indicates that the probability of exploitation is very low but not zero; the vulnerability is not listed in the CISA KEV catalog. Without a patch, any exposed bRPC service is at risk of sustained denial of service.

Generated by OpenCVE AI on October 30, 2026 at 17:31 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade Apache bRPC to version 1.18.0, which limits accumulated payloads and rejects oversized fragments
  • If an upgrade is not immediately possible, apply the upstream patch from pull request 3489 to enforce the size limit
  • For legitimate use cases requiring larger fragments, adjust the gflag max_body_size after applying the fix, and ensure that streams from untrusted clients are appropriately filtered or rate‑limited

Generated by OpenCVE AI on October 30, 2026 at 17:31 UTC.

Tracking

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Advisories

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History

Fri, 30 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 22 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
First Time appeared Apache
Apache brpc
Vendors & Products Apache
Apache brpc

Wed, 21 Oct 2026 12:00:00 +0000

Type Values Removed Values Added
Description Unbounded memory accumulation in the stream message reassembly path of Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to exhaust the memory of a server (denial of service) by sending an endless sequence of continuation data frames. Root Cause: The streaming RPC protocol bounds every single data frame by max_body_size, but a fragmented stream message accumulates continuation frames into one buffer (_pending_buf) without any limit on the accumulated size. A malicious peer that can open a stream can therefore keep sending continuation frames to make the receiver accumulate an arbitrarily large in-memory message. Since the default flow-control settings (socket_max_streams_unconsumed_bytes=0) do not throttle the sending rate, the receiver's memory grows until the process runs out of memory and crashes or becomes unavailable. Affected Scenarios: Services that accept streams from untrusted clients (for example using brpc::StreamAccept or brpc::StreamCreate with the built-in streaming protocol) are affected. 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/3489 Note: The fix limits the accumulated payload of a fragmented stream message to max_body_size (default 64MB). When the accumulated payload exceeds the limit, the pending fragments are released and the stream is closed with error EMSGSIZE. After applying the fix, legitimate fragmented stream messages larger than max_body_size will be rejected; you can adjust the gflag max_body_size to change the limit.
Title Apache bRPC: Unbounded Memory Accumulation in Stream Message Reassembly
Weaknesses CWE-770
References

Subscriptions

Apache Brpc
cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-10-30T14:18:35.910Z

Reserved: 2026-08-26T12:29:39.167Z

Link: CVE-2026-80463

cve-icon Vulnrichment

Updated: 2026-10-30T14:17:48.441Z

cve-icon NVD

Status : Deferred

Published: 2026-10-21T12:17:24.093

Modified: 2026-10-30T15:16:55.067

Link: CVE-2026-80463

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-30T17:45:15Z

Weaknesses
  • CWE-770

    Allocation of Resources Without Limits or Throttling