Answer in brief
CVE-2026-84969 records a Medium severity (CVSS 3.7) vulnerability in Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output. The current sources do not mark it as known exploited. The current feed maps MongoDB/C Driver (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 3.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps MongoDB/C Driver (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:mongodb:c_driver:*:*:*:*:*:mongodb:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| MongoDB/C Drivergeneric | >=1.30.0 <1.30.9 || >=2.0.0 <2.5.2 | 1.30.9, 2.5.2 |
Published upstream
Sep 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 3, 2026
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.
Quoted source text, attributed separately from HOL analysis.