What is CVE-2026-120821?

CVE-2026-120821 is a medium-severity vulnerability in MongoDB Server, classified under Use After Free. CVSS score: 6.5/10. Published 2026-11-10.

How severe is CVE-2026-120821?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Use After Free in MongoDB Server

CVE-2026-120821

A use-after-free in the aggregation framework of MongoDB Server can occur when certain expressions are evaluated in an aggregation sub-pipeline. The condition can be caused by an authenticated user with read privileges, and may result in the server terminating unexpectedly.

Vulnerability class: Use-After-Free

Published 2026-11-10 · last modified 2026-11-10.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

MongoDB Server

Weakness classification (CWE)

CWE-416 — Use After Free

References

jira.mongodb.org/browse/SERVER-136285

Frequently asked questions

What is CVE-2026-120821?: CVE-2026-120821 is a medium-severity vulnerability in MongoDB Server, classified under Use After Free. CVSS score: 6.5/10. Published 2026-11-10.
How severe is CVE-2026-120821?: Medium severity. CVSS v3 base score is 6.5 out of 10.