Use After Free in MongoDB
CVE-2026-8336
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- MongoDB
- MongoDB, Inc. MongoDB Server — versions 7.0, 8.0, 8.2
Weakness classification (CWE)
References
- jira.mongodb.org/browse/SERVER-121610 (issue-tracking, Issue Tracking, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-8336?
- CVE-2026-8336 is a high-severity vulnerability in MongoDB, classified under Use After Free. CVSS score: 7.5/10. Published 2026-05-13.
- How severe is CVE-2026-8336?
- High severity. CVSS v3 base score is 7.5 out of 10.