What’s Vulnerable › Vulnerabilities
CVE-2026-84969: Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output
- Severity: low (CVSS 3.7 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.3% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-09-03 · updated 2026-09-10
- Weakness: CWE-787
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.
Affected products
- MongoDB C# Driver: from 1.30.0 before 1.30.9; from 2.0.0 before 2.5.2 — fixed in 1.30.9, 2.5.2
How to fix
Upgrade to a fixed version: MongoDB C# Driver 1.30.9, 2.5.2. Check the vendor advisory for mitigations.
References
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