Medium severity · published May 13, 2026
CVE-2026-8336
Post-authentication use-after-free error in $_internalJsEmit and mapreduce commands
6.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 17% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MO
MongoDB · MongoDB
8.2.0 before 8.2.9; 8.3.0 before 8.3.2 · source: NVD
MS
MongoDB Server · MongoDB, Inc.
8.2 before 8.2.9; 8.3 before 8.3.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-8336
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-8336
Issue Tracking
https://jira.mongodb.org/browse/SERVER-121610
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