CVE-2026-96749
Heap out-of-bounds write via signed size overflow in BSON document encoding
Description
An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party with no privileges who can place a very large value into data that an application encodes may, depending on how the native extension was built, cause a write outside the bounds of an allocated buffer inside the application's own process.
INFO
Published Date :
Sept. 24, 2026, 7:17 p.m.
Last Modified :
Sept. 24, 2026, 9 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | a39b4221-9bd0-4244-95fc-f3e2e07f1deb | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | a39b4221-9bd0-4244-95fc-f3e2e07f1deb | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update the MongoDB Python Driver to the latest version.
- Rebuild the native extension if using a custom build.
- Avoid encoding excessively large documents.
- Sanitize caller-supplied data before encoding.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-96749.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-96749 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-96749
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-96749 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-96749 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by [email protected]
Sep. 24, 2026
Action Type Old Value New Value Added Reference https://github.com/mongodb/mongo-python-driver/security/advisories/GHSA-v4x9-3549-crwv -
New CVE Received by [email protected]
Sep. 24, 2026
Action Type Old Value New Value Added Description An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party with no privileges who can place a very large value into data that an application encodes may, depending on how the native extension was built, cause a write outside the bounds of an allocated buffer inside the application's own process. Added CVSS V4.0 AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-190 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/96xxx/CVE-2026-96749.json">CVE-2026-96749</a> Added Reference https://github.com/mongodb/mongo-python-driver/blob/4.18.2/doc/changelog.rst Added Reference https://github.com/mongodb/mongo-python-driver/releases/tag/4.18.2 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 24, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-96749', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-24T18:36:53.836151Z'}