# CVE-2026-18709: Missing Authorization in MongoDB Sharded Transaction Commit/Abort Handling Leads to Cross-Shard Data Inconsistency

CVE-2026-18709 is fixed in MongoDB on 1 platform by MongoDB 8.3.11 (version 8.3.11), released September 9, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-18709
- Priority: Routine
- CVSS: 5.9
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 11, 2026
- Weakness: CWE-862: Missing Authorization
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-18709

## Description

An issue in MongoDB Server could allow an authenticated user with direct network access to a shard to improperly commit or abort an in-progress prepared transaction, bypassing the intended transaction coordination process. This could result in cross-shard data inconsistency, cluster clock corruption, and violation of transaction atomicity guarantees.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | MongoDB | 8.3.11 | [MongoDB 8.3.11](https://patchblox.com/security/data/fix/windows-app/mongodb.server-8.3.11.md) | Sep 9, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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