# CVE-2026-120678: MongoDB C Driver leaks the decompressed reply buffer when an OP_COMPRESSED reply fails to parse (denial of service)

> CVE-2026-120678: MongoDB C Driver leaks the decompressed reply buffer when an OP_COMPRESSED reply fails to parse (denial of service). CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-120678
Last updated: 2026-11-03T21:17:04Z

- Published: 2026-11-03 18:39 UTC · Updated: 2026-11-03 21:17 UTC · Assigner: mongodb
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.39%, 33th percentile (scored 2026-11-04)
- CISA KEV: no
- CWE: CWE-401

## Description

A memory management flaw in the MongoDB C Driver's handling of compressed responses may cause the client library to hold on to memory that is never released. An unauthenticated party that controls the database endpoint a client application connects to may cause repeated, unbounded memory growth in that application, which may result in the application becoming unavailable. No credentials, transport security settings, or user interaction are required.

## Affected vendors and products

- MongoDB: C Driver

## Tracked companies

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

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-120678)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-120678)
- [https://jira.mongodb.org/browse/CDRIVER-6521](https://jira.mongodb.org/browse/CDRIVER-6521)

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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-2026-120678 · Markdown: https://rewindex.com/cve/CVE-2026-120678.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-120678 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-11-05T15:28:17.515Z