What is the CVSS score of CVE-2026-65815?

CVE-2026-65815 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.9%.

Which versions of Microsoft Dynamics 365 are affected by CVE-2026-65815?

Microsoft Dynamics 365 on-premises installations are vulnerable to remote code execution (CVE-2026-65815) that allows any authenticated user to fully compromise the server and access all business…. A patch is available.

How to fix or mitigate CVE-2026-65815?

Within 24 hours, inventory all on-premises Dynamics 365 instances, identify those processing critical business data or supporting essential operations, and assess the population of authenticated users with access. Within 7 days, implement compensating controls including network segmentation to isolate Dynamics 365 servers from untrusted networks, enforce multi-factor authentication (MFA) for all user access to these instances, deploy network-based intrusion detection for deserialization payloads, and enable comprehensive audit logging of authentication and serialization activities. Within 30 days, establish regular contact with Microsoft Security Response Center regarding patch timelines, evaluate the feasibility of migrating to Dynamics 365 cloud-hosted solutions, conduct application-level code reviews to identify potential gadget chain exposures, and develop an incident response plan specific to deserialization-based attacks.

Microsoft Dynamics 365 CVE-2026-65815

EUVD-2026-56449 HIGH

Deserialization of Untrusted Data (CWE-502)

2026-08-11 secure@microsoft.com

GHSA-83pg-fr4f-gxq5

Deserialization Microsoft Dynamics 365

8.8

CVSS 3.1 · Vendor: microsoft

Severity by source

Vendor (microsoft) PRIMARY

8.8 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

vuln.today AI

8.8 HIGH

Network-reachable endpoint (AV:N), no special conditions (AC:L), low-privilege credential required (PR:L); full C/I/A impact is consistent with arbitrary code execution via deserialization gadget chain.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Patch available

Aug 11, 2026 - 18:19 EUVD

Analysis Generated

Aug 11, 2026 - 18:15 vuln.today

CVE Published

Aug 11, 2026 - 17:19 nvd

HIGH 8.8

DescriptionCVE.org

Deserialization of untrusted data in Microsoft Dynamics 365 (on-premises) allows an authorized attacker to execute code over a network.

AnalysisAI

Remote code execution in Microsoft Dynamics 365 on-premises is achievable by any authenticated low-privileged user via a crafted deserialization payload sent over the network, yielding full confidentiality, integrity, and availability compromise of the affected host. The root cause is CWE-502 (Deserialization of Untrusted Data), a class of vulnerability historically weaponized effectively in .NET-based enterprise applications through gadget chains. No public exploit code or CISA KEV listing was identified at the time of analysis, but the combination of low attack complexity, low privilege requirement, and high CIA impact makes this a credible, high-priority remediation target for organizations running Dynamics 365 on-premises.

Technical ContextAI

Microsoft Dynamics 365 on-premises is an enterprise resource planning and customer relationship management platform built heavily on the Microsoft .NET stack. CWE-502 (Deserialization of Untrusted Data) arises when an application deserializes input from an untrusted source without adequate type validation or restriction, allowing an attacker to supply a crafted object graph that executes arbitrary code during the deserialization process. In .NET environments this commonly involves gadget chains exploited through mechanisms such as BinaryFormatter, LosFormatter, DataContractSerializer, or third-party serialization libraries. The CVSS vector (AV:N/AC:L/PR:L) confirms the vulnerable endpoint is reachable over a network by any authenticated account with no elevated privilege or special configuration required beyond a valid credential. No CPE strings were provided in the source data, so the exact affected internal component and precise version range within the Dynamics 365 on-premises product line cannot be pinpointed from the available intelligence alone.

RemediationAI

Consult the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-65815 and apply the update issued for the affected Dynamics 365 on-premises version. Patch available per vendor advisory; no exact patch version number was present in the provided data, and the precise update package designation must be retrieved from the MSRC update guide directly. As a compensating control where immediate patching is not feasible, restrict network access to the Dynamics 365 on-premises application server to only trusted internal network segments or VPN-connected endpoints, reducing the pool of accounts that can submit serialized payloads - note this does not eliminate risk from insider threats or already-compromised credentials. Auditing and removing stale or unnecessary low-privilege Dynamics 365 accounts further limits the credential surface available to an attacker. Where the platform supports it, enabling application-layer logging on serialization-related endpoints may provide early detection of crafted payload attempts.