This issue can occur when running an aggregation pipeline that uses the internal $exchange stage configured with key-range partitioning and order-preserving delivery. If a single key range produces enough documents to fill its exchange buffer (that is, many results are routed to the same consumer), the server reaches the code path where a full per-consumer buffer is detected but the internal "high watermark" for that key range is not updated as intended.

Project Subscriptions

Vendors Products
Mongodb Subscribe
Mongodb Server Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 10 Jun 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 10 Jun 2026 00:45:00 +0000

Type Values Removed Values Added
First Time appeared Mongodb
Mongodb mongodb Server
Vendors & Products Mongodb
Mongodb mongodb Server

Tue, 09 Jun 2026 22:30:00 +0000

Type Values Removed Values Added
Description This issue can occur when running an aggregation pipeline that uses the internal $exchange stage configured with key-range partitioning and order-preserving delivery. If a single key range produces enough documents to fill its exchange buffer (that is, many results are routed to the same consumer), the server reaches the code path where a full per-consumer buffer is detected but the internal "high watermark" for that key range is not updated as intended.
Title Using MaxKey() may crash the server
Weaknesses CWE-617
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: mongodb

Published:

Updated: 2026-06-10T13:32:50.141Z

Reserved: 2026-05-27T17:47:39.152Z

Link: CVE-2026-9749

cve-icon Vulnrichment

Updated: 2026-06-10T13:32:45.491Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-06-09T23:17:04.380

Modified: 2026-06-10T19:43:28.857

Link: CVE-2026-9749

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-10T00:30:16Z

Weaknesses