Security readout for executives and security teams
Plain-English summary
This critical flaw lets an unauthenticated network attacker run code on vulnerable on-premises SharePoint servers. Successful exploitation could expose documents, alter systems, disrupt services, and enable broader compromise. Microsoft reports exploitation in the wild, and CISA lists the vulnerability as known exploited.
Executive priority
Immediate, highest-priority action is warranted. Assign accountable owners for exposure identification, mitigation, updating, and compromise assessment. Because exploitation is confirmed, remediation alone is insufficient for systems that were reachable while vulnerable; leadership should require evidence of both protection and incident review.
Technical view
CVE-2025-53770 is an untrusted-data deserialization vulnerability, CWE-502, affecting listed on-premises SharePoint Server products. It is remotely reachable, requires no privileges or user interaction, and can compromise confidentiality, integrity, and availability. CVSS 3.1 score: 9.8.
Likely exposure
Exposure is highest for network-accessible or internet-facing SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition deployments. The bundle lists version 16.0.0 for each product but does not provide precise vulnerable build ranges, so administrators must confirm applicability through Microsoft’s advisory.
Exploitation context
Active exploitation is confirmed by Microsoft, and CISA includes CVE-2025-53770 in its Known Exploited Vulnerabilities catalog. The bundle also states that an exploit exists publicly or operationally. It does not establish which organizations are targeted, the total attack scale, or specific compromise indicators.
Researcher notes
The source bundle supports unauthenticated network RCE through unsafe deserialization and confirmed exploitation. It does not provide vulnerable build boundaries, exploit-chain details, reliable indicators, or named update identifiers. Avoid inferring those details. Validate current remediation requirements directly against Microsoft because the bundled description reflects an earlier update-preparation state.
Mitigation direction
- Review Microsoft’s current advisory for applicable security updates and deployment instructions.
- Apply Microsoft’s documented mitigation immediately wherever updating cannot be completed.
- Restrict network access to affected SharePoint servers until protections are verified.
- Treat previously exposed vulnerable servers as potentially compromised and begin incident-response review.
- Prioritize backups and recovery readiness before performing emergency remediation.
Validation and detection
- Inventory all on-premises SharePoint servers, editions, versions, and externally reachable interfaces.
- Compare installed build and update levels with Microsoft’s current CVE advisory.
- Verify Microsoft’s documented mitigation is enabled and operating as intended.
- Review SharePoint, web, authentication, and endpoint telemetry for anomalous activity.
- Escalate suspicious findings for forensic investigation; the bundle provides no specific indicators.
Public sources used
The source record changed after analysis: Material source record changed after analysis.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2025-53770 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:W/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:W/RC:C3.95.9microsoftVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:W/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2025-53770 added to CISA KEV
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2025-07-20T00:00:00.000Z: CVE-2025-53770 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- Microsoft SharePoint Server Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53770CVE reference, CISA-ADP · government-resource
- https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/CVE reference, CVE
- https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770CVE reference, CVE
- https://research.eye.security/sharepoint-under-siege/CVE reference, CVE
- https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/CVE reference, CVE
- https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/CVE reference, CVE
- https://x.com/Shadowserver/status/1946900837306868163CVE reference, CVE
- https://github.com/kaizensecurity/CVE-2025-53770CVE reference, CVE
- https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globallyCVE reference, CVE
- https://news.ycombinator.com/item?id=44629710CVE reference, CVE
- https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/CVE reference, CVE
- https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flawCVE reference, CVE
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.