Silent data alteration via oversized JSON strings
Published Sep 3, 2026 · Updated Sep 3, 2026
Incorrect numeric conversion in MongoDB C Driver 1.10.0 through 1.30.8 and 2.0.0 through 2.5.1 allows remote attackers to alter data. The BSON JSON parser casts an unusually large string length to int without range validation, so it silently shortens the value or omits its field while reporting success. The attacker must supply JSON that a linked application parses; the bounded consequence is unintended alteration of application-held data.
Summary
What happened
Incorrect numeric conversion in MongoDB C Driver 1.10.0 through 1.30.8 and 2.0.0 through 2.5.1 allows remote attackers to alter data. The BSON JSON parser casts an unusually large string length to int without range validation, so it silently shortens the value or omits its field while reporting success. The attacker must supply JSON that a linked application parses; the bounded consequence is unintended alteration of application-held data.
The record
- CVE
- CVE-2026-84963
- Published
- Sep 3, 2026
- Updated
- Sep 3, 2026
- Vendor
- MongoDB
- Product
- MongoDB C++ Driver
- Classifications
- CWE-681, T1565
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 3, 2026CVE publishedPublication date reported by the CVE source.
- Sep 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.10.0 <1.30.9
- Affected versionversion=2.0.0 <2.5.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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