6.3

CVE-2026-84969: mongodb c_driver Out-of-bounds Write

CVSS: 6.3v4.0MediumAnalyzed
AliasesUBUNTU-CVE-2026-84969DEBIAN-CVE-2026-84969
Published 03-09-2026Last modified 03-09-2026
Open JSON

Vulnerability summary

CVE-2026-84969 is a medium (CVSS 6.3) Out-of-bounds Write vulnerability in mongodb c_driver. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 18.1% of scored vulnerabilities.

Overall risk
25/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.27%
0%100%
Low · +0.11 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:11706-1

Timeline

  1. 03-09-2026
    PublishedVulnerability first disclosed.
  2. 03-09-2026
    Last modifiedVulnerability information updated.

Description

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

CVSS metrics

7 scores · 4 sources · 2 versions

EPSS trend

Probability

0.27%

Chance of exploitation in the next 30 days

Percentile

18%

Versus all other CVEs

30-day change

+0.11 pp

From 0.17% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.27%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • mongo-c-driverAll versions (No fix recorded) | < 2.5.2-1
Mongodb1 product
  • c_driver≥ 1.30.0, < 1.30.9 | ≥ 2.0.0, < 2.5.2
Ubuntu1 product
  • mongo-c-driverAll versions (No fix recorded)

3 vendors · 3 products

References

4 links