EUVD-2026-56433
GHSA-j9wh-7m6g-7824
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Network-accessible endpoint requires low-privilege account (PR:L); deserialization is straightforward once authenticated (AC:L); full server compromise yields high C/I/A with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3DescriptionCVE.org
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
AnalysisAI
Remote code execution in Microsoft SharePoint Server allows a network-authenticated attacker with low-level privileges to execute arbitrary code by exploiting unsafe deserialization of attacker-controlled data. Both SharePoint Server 2019 and the Subscription Edition are confirmed affected, with patches available from Microsoft. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to hold any valid, authenticated account on the target SharePoint Server instance (PR:L); unauthenticated exploitation is not supported by the CVSS vector. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 8.8 with vector AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H accurately reflects a serious, network-exploitable deserialization flaw requiring only low privileges and no user interaction. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with a low-privilege SharePoint account - such as a contractor, external partner, or employee with read-only access - crafts a malicious serialized .NET object and submits it to a vulnerable SharePoint API endpoint over the network. SharePoint deserializes the payload without adequate type validation, triggering a known .NET gadget chain that results in arbitrary OS-level command execution under the SharePoint application pool identity. … |
| Remediation | Apply the vendor-released patches immediately: upgrade SharePoint Server Subscription Edition to build 16.0.19725.20522 or later, and SharePoint Server 2019 to build 16.0.10417.20198 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all SharePoint Server instances in your environment, including both SharePoint Server 2019 and Subscription Edition deployments, and assess current patch levels against Microsoft's advisory. …
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Same weakness CWE-502 – Deserialization of Untrusted Data
View allSame technique Deserialization
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External POC / Exploit Code
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