# CVE-2026-8336: Post-authentication use-after-free error in $_internalJsEmit and mapreduce commands

> CVE-2026-8336: Post-authentication use-after-free error in $_internalJsEmit and mapreduce commands. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-8336
Last updated: 2026-06-17T11:03:49Z

- Published: 2026-05-13 00:16 UTC · Updated: 2026-06-17 11:03 UTC · Assigner: mongodb
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS: 0.26%, 17th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-416

## Description

After invoking $\_internalJsEmit, which is not intended to be directly accessible, or mapreduce command’s map function in a certain way, an authenticated user can subsequently crash mongod when the server-side JavaScript engine (through $where, $function, mapreduce reduce stage, etc.) is used also in a specific way, resulting in a post-authentication denial-of-service. This issue impacts MongoDB Server v8.2 versions prior to 8.2.9 and v8.3 versions prior to 8.3.2.

## Affected vendors and products

- MongoDB, Inc.: MongoDB Server

## Tracked companies

- [MongoDB Atlas](https://rewindex.com/company/mongodb-atlas.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-8336)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-8336)
- [https://jira.mongodb.org/browse/SERVER-121610](https://jira.mongodb.org/browse/SERVER-121610)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-8336 · Markdown: https://rewindex.com/cve/CVE-2026-8336.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-8336 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:46.203Z