VDB-396398 · CVE-2026-81528 · GCVE-0-2026-81528

MongoDB C# Driver up to 3.11.0 Document Replacement neutralization

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.7	$0-$5k	1.90-

Summaryinfo

A vulnerability, which was classified as critical, was found in MongoDB C# Driver up to 3.11.0. This affects an unknown part of the component Document Replacement. Such manipulation leads to neutralization. This vulnerability is listed as CVE-2026-81528. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as critical, has been found in MongoDB C# Driver up to 3.11.0. Affected by this issue is some unknown functionality of the component Document Replacement. The manipulation with an unknown input leads to a neutralization vulnerability. Using CWE to declare the problem leads to CWE-707. The product does not ensure or incorrectly ensures that structured messages or data are well-formed and that certain security properties are met before being read from an upstream component or sent to a downstream component. Impacted is confidentiality, integrity, and availability. CVE summarizes:

A MongoDB C# driver document-replacement code path omits the element-name/shape validation that the equivalent write paths apply, so a value supplied as a replacement is forwarded to the server without neutralization of query-language special elements. An application that passes untrusted, loosely-typed input as a replacement value therefore allows that input to be interpreted by the database as update logic rather than as data, executing under the application's own database credentials. Applications using strongly-typed document mappings are not affected.

The advisory is available at nuget.org. This vulnerability is handled as CVE-2026-81528 since 08/27/2026. The exploitation is known to be easy. The attack may be launched remotely. The technical details are unknown and an exploit is not available.

Upgrading to version 3.11.1 eliminates this vulnerability.

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Productinfo

Type

Database Software

Vendor

MongoDB

Name

C# Driver

Version

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.7

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.4
CNA Vector (mongodb): 🔒

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Neutralization
CWE: CWE-707 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: C# Driver 3.11.1

Timelineinfo

08/27/2026 Advisory disclosed
08/27/2026 +0 days CVE reserved
08/27/2026 +0 days VulDB entry created
08/27/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: nuget.org
Status: Confirmed

CVE: CVE-2026-81528 (🔒)
GCVE (CVE): GCVE-0-2026-81528
GCVE (VulDB): GCVE-100-396398

Entryinfo

Created: 08/27/2026 23:10
Changes: 08/27/2026 23:10 (76)
Complete: 🔍
Cache ID: 216::103