# CVE-2026-18687: Improper Validation in MongoDB Queryable Encryption Maintenance Operation Leads to Denial of Service and Index Corruption

CVE-2026-18687 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: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-18687
- Priority: High
- CVSS: 7.1
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 11, 2026
- Weakness: CWE-191: Integer Underflow (Wrap or Wraparound)
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-18687

## Description

MongoDB Server's handling of a Queryable Encryption maintenance operation did not properly validate certain request parameters against the collection's encrypted field configuration before use. An authenticated user with readWrite privileges could submit a specially formed request that leads to a server crash or excessive internal writes, resulting in resource exhaustion and corruption of encrypted index data.

## 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 2026-11-09T13:31:49Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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