Medium severity · published Sep 3, 2026
CVE-2026-84963
Silent field truncation via unchecked int cast of huge JSON string values in JSON-to-BSON parser
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what was submitted, which may result in unintended alteration of data.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
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 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MO
MongoDB · MongoDB
1.10.0 before 1.30.9; 2.0.0 before 2.5.2 · source: vendor
CD
C Driver · Mongodb
1.10.0 before 1.30.9; 2.0.0 before 2.5.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-84963
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-84963
Vendor Advisory
https://jira.mongodb.org/browse/CDRIVER-6407
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