Low severity · published Sep 3, 2026
CVE-2026-84969
Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output
3.7
CVSS
0.3%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MO
MongoDB · MongoDB
1.30.0 before 1.30.9; 2.0.0 before 2.5.2 · source: vendor
CD
C Driver · Mongodb
1.30.0 before 1.30.9; 2.0.0 before 2.5.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-84969
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-84969
Vendor Advisory
https://jira.mongodb.org/browse/CDRIVER-6410
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