Use After Free in MongoDB Server
CVE-2026-120803
A use-after-free issue exists in MongoDB’s SBE (Slot-Based Execution) implementation of a window function accumulator used by certain $setWindowFields aggregation pipelines. Under specific conditions, the accumulator can retain a dangling pointer to memory that has since been freed. When this stale pointer is later dereferenced during serialization of the carried-forward value, it can result in a heap out-of-bounds read that may expose adjacent heap contents and crash the mongod server. An authenticated user with readWrite privileges on a database can trigger this issue by crafting a specific aggregation pipeline.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-120803?
- CVE-2026-120803 is a high-severity vulnerability in MongoDB Server, classified under Use After Free. CVSS score: 7.1/10. Published 2026-11-10.
- How severe is CVE-2026-120803?
- High severity. CVSS v3 base score is 7.1 out of 10.