MongoDBGHSA-8vwp-6h6c-hx6h
Silent field truncation via unchecked int cast of huge JSON string values in JSON-to-BSON parser
Medium6.3CVE-2026-84963 · Published Sep 3, 2026
### Impact 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. ### Patches Fixed in 1.30.9 and 2.5.2 ### Workarounds Validate length of inputs before processing JSON. ### References https://jira.mongodb.org/browse/CDRIVER-6407
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| MongoDB C Driver Product | >= 1.10.0, < 1.30.9 | 1.30.9 |
| >= 2.0.0, < 2.5.2 | 2.5.2 |
Details and references
- CVSS 4.0
- CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- Severity from
- GitHub (reviewed advisory)
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