# CVE-2026-18693: Out-of-Bounds Read/Write in MongoDB Timeseries Bucket Handling Leads to Denial of Service and Potential Memory Disclosure

CVE-2026-18693 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-2026-18693
- Priority: High
- CVSS: 7.2
- EPSS: 0.0034
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 11, 2026
- Weakness: CWE-787: Out-of-bounds Write
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-18693

## Description

An issue in MongoDB Server's handling of timeseries collections could allow an authenticated user with write privileges to cause an internal data structure to become inconsistent through certain document insertions. A subsequent insert into the affected bucket could then result in the server accessing memory outside its intended bounds, potentially causing a server crash (denial of service), exposure of limited memory contents, or memory corruption.

## 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 |

---

Data as of 2026-11-08T06:59:42Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.