CVE intelligence and bounded remediation
CVE-2025-53770 — Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute code over a network. Microsoft is aware that an exploit for CVE-2025-53770 exists in the wild. Microsoft is preparing and fully testing a comprehensive update to address this vulnerability. In the meantime, please make sure that the mitigation provided in this CVE documentation is in place so that you are protected from exploitation.
- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Published
- 2025-07-20
- CISA KEV
- Known exploited
- Ecosystem
- windows/system
- Weaknesses
- CWE-502
Affected products
- microsoft / sharepoint_server
- microsoft / sharepoint_server / 2016
- microsoft / sharepoint_server / 2019
Matched remediation archetype
Unsafe deserialization and object reconstruction
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Inventory serialization formats accepted from requests, queues, caches, files, cookies, and cross-service messages.
- Trace whether untrusted input can select classes, types, callbacks, constructors, or object hooks during decoding.
- Identify signing, schema validation, trust-boundary, and compatibility settings for each decoder.
Remediate safely
- Replace native object deserialization with a data-only format and explicit schema validation.
- If replacement is not immediate, use a safe decoder with a minimal type allowlist and disable polymorphic or executable hooks.
- Update the affected library and add inert tests for unknown types, extra fields, malformed nesting, and unsigned data.
Authoritative sources
Complete CVE record and remediation plan
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