# CVE-2026-120818: Use-After-Free in MongoDB Server JavaScript Support for Aggregation Leads to Information Disclosure

Status: published. Published: 2026-11-10. Updated: 2026-11-13.

A use-after-free weakness in MongoDB Server's server-side JavaScript support for aggregation may allow a stale reference to previously freed process memory to be read and returned. An authenticated user with minimal or no assigned roles can trigger this condition over the normal network protocol by submitting a single crafted aggregation request, with no additional privileges or non-default configuration. Successful triggering this issue may result in adjacent process memory contents being returned, including data that undermines memory-layout randomization, and may in some cases affect server availability.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- MongoDB / MongoDB Server: ≥ 8.3.0; < 8.3.16 (affected, semver); ≥ 8.0.0; < 8.0.37 (affected, semver); ≥ 7.0.0; < 7.0.48 (affected, semver). Source: CNA: mongodb

## Severity and prioritization

- CVSS 4.0: 7.1 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N; source: CNA: mongodb

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L; source: CNA: mongodb

- CVSS 4.0: 7.1 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: cna@mongodb.com

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L; source: NVD: cna@mongodb.com

- CISA KEV: No listing in collected sources

- EPSS: 0.40% as of 2026-11-13; percentile 34.29%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-416

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://jira.mongodb.org/browse/SERVER-135727 (CNA: mongodb)

- https://jira.mongodb.org/browse/SERVER-135727 (cna@mongodb.com)

## Provenance

- CNA: mongodb: https://www.cve.org/CVERecord?id=CVE-2026-120818; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-120818; retrieved 2026-11-11; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-120818; retrieved 2026-11-13; source updated Not reported

Revision: 4f1c8ad1c31479c30390f8ac15a22471126ee8f379ac1a2b05ff2a61dbc78c4b

Canonical: https://y2.dev/cve/CVE-2026-120818

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Collected public records only. Check source status for coverage and freshness.