CVE-2026-6691
Heap Buffer Overflow in MongoDB C Driver with Cyrus SASL
Publication date: 2026-05-06
Last updated on: 2026-05-06
Assigner: MongoDB, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mongodb | mongodb_c_driver | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-120 | The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
The vulnerability exists in the MongoDB C Driver's Cyrus SASL integration, where unsafe string copying occurs during the process of username canonicalization. This unsafe operation can lead to a heap buffer overflow before any authentication or network traffic takes place. The issue can be triggered by providing untrusted input in the username field of a MongoDB URI when using the authMechanism=GSSAPI.
How can this vulnerability impact me? :
This vulnerability can lead to a heap buffer overflow, which may allow an attacker to execute arbitrary code or cause a denial of service. Since the overflow occurs before authentication or network traffic, it could be exploited remotely by passing malicious input in the username field, potentially compromising the security and stability of the affected system.