CVE-2025-14911: 
Linux Debian vulnerability analysis and mitigation

CVE-2025-14911 is a buffer overflow vulnerability in the MongoDB C Driver (mongo-c-driver) affecting versions prior to 2.1.3. The flaw exists in the handling of GridFS metadata: user-controlled chunkSize values lack appropriate validation, allowing malformed GridFS metadata to overflow the bounding container. It was published on January 27, 2026, with MongoDB as the assigning CNA. The vulnerability carries a CVSS v3.1 base score of 6.5 (Medium) and a CVSS v4.0 base score of 7.1 (High) (Feedly, MongoDB JIRA).

The root cause is classified as CWE-120 (Buffer Copy without Checking Size of Input — 'Classic Buffer Overflow'). When an authenticated user supplies a malformed chunkSize field in GridFS file metadata, the mongo-c-driver processes this value without adequate bounds checking, causing the value to overflow the allocated buffer or container used during GridFS chunk operations. The attack vector is network-based, requires low privileges (authenticated access), and no user interaction, making it straightforward to trigger for any user with database write or insert access. No public proof-of-concept exploit code has been identified at this time (Feedly, MongoDB JIRA).

Successful exploitation results in a denial-of-service condition, crashing or disrupting GridFS file retrieval and storage operations within applications using the affected mongo-c-driver. The impact is limited to availability (no confidentiality or integrity impact), but any service relying on GridFS for file storage — such as media platforms, document management systems, or data pipelines — could experience significant outages. Lateral movement or data exfiltration are not directly enabled by this vulnerability (Feedly).

No public exploit code or active in-the-wild exploitation has been reported for CVE-2025-14911. The EPSS score is approximately 0.04%, indicating a low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires authenticated access to a MongoDB instance using the affected driver, which limits the attacker pool but does not eliminate risk in multi-tenant or shared environments (Feedly, Tenable).

1. Reconnaissance: Identify applications using the MongoDB C Driver (mongo-c-driver) versions prior to 2.1.3 that expose GridFS file upload or metadata manipulation functionality.
2. Obtain credentials: Acquire low-privilege authenticated access to the target MongoDB instance (e.g., via credential theft, default credentials, or a legitimate user account).
3. Craft malformed GridFS metadata: Prepare a GridFS file insertion request with a deliberately malformed or excessively large chunkSize value in the file metadata document (e.g., a negative integer, zero, or an integer exceeding expected bounds).
4. Submit the malicious request: Insert the crafted GridFS file metadata into the MongoDB database using the mongo-c-driver API or a compatible client.
5. Trigger the overflow: The driver processes the malformed chunkSize without validation, causing a buffer overflow in the bounding container and resulting in a crash or denial-of-service condition for the affected GridFS operation (Feedly, MongoDB JIRA).

• Logs: Application or MongoDB driver logs showing unexpected crashes, segmentation faults, or errors during GridFS read/write operations; error messages referencing chunkSize or GridFS chunk processing failures.
• Process: Abnormal termination (crash) of processes using the mongo-c-driver, particularly during GridFS file retrieval or storage operations.
• Database: GridFS fs.files collection entries with anomalous or out-of-range chunkSize field values (e.g., negative numbers, zero, or extremely large integers) inserted by non-administrative users.

MongoDB has released version 2.1.3 of the mongo-c-driver, which addresses this vulnerability by adding proper validation of the user-controlled chunkSize metadata field. Users should upgrade to mongo-c-driver 2.1.3 or later as the primary remediation (MongoDB JIRA, Feedly). As a workaround prior to patching, restrict database write access to trusted users only and validate chunkSize values at the application layer before passing them to the driver. Monitor GridFS collections for anomalous metadata entries.