TIRESIS/Forecast/CVE-2025-53770
⚡ CISA KEV — Actively ExploitedCRITICAL RISK

CVE-2025-53770

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 t…

SMB Attack Probability Score
95/100critical
Weighted: EPSS · CISA KEV · SMB stack prevalence · exploit maturity · CVSS vector
CVSS v3
9.8
EPSS (30d)
90.49%
SMB Exposure
85.5/100
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
💻
SMB Impact
How this vulnerability affects a real small business
1
How this breaks an SMB

Operating system vulnerability enables privilege escalation or remote code execution — giving attackers full control over affected machines within the network.

2
Typical real-world scenario

Initial foothold (phishing or exposed service) triggers OS exploit. Domain admin privileges are obtained. Ransomware is deployed network-wide overnight.

3
Estimated downtime & cost
Est. downtime
5–14 days
Business cost range
€20K–€150K
4
What IT should check this week
Are all Windows/macOS systems updated within the last 30 days?
Is Windows Defender or equivalent AV active and updated?
Are local admin rights restricted to only necessary users?
Are domain admin accounts used only for admin tasks?
Scenarios are generated based on software category and CVE characteristics. Cost ranges reflect SMB incidents in TIRESIS incident database.
Threat Evolution Timeline
From disclosure to predicted exploitation — 7 events
◈ 2 predicted
📋
20 Jul 2025
Vulnerability disclosed
CVE published by NVD with CVSS 9.8 (CRITICAL)
🚨
20 Jul 2025CISA KEV
Added to CISA KEV catalog
CISA confirms active exploitation. Disconnect public-facing versions of SharePoint Server that have reached their end-of-life (EOL) or end-of-service (EOS) to include SharePoint Server 2013 and earlier versions. For supported versions, please follow the mitigations according to CISA (URL listed below in Notes) and vendor instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.
⚡
22 Jul 2025
Exploit in the wild
Active exploitation observed — automated scanning and targeted attacks underway
🔬
23 Jul 2025
Proof-of-Concept published
Public PoC code available — exploitation now accessible to non-expert attackers
📍
TODAY
Today
EPSS: 90.5% probability of exploitation in next 30 days. SMB Risk Score: 95/100
Forecast →
🌐
7 May 2026◈ predicted · in 7 days
Predicted: mass exploitation window
Based on EPSS 90% and current exploit maturity — automated scanning campaigns expected at scale.
⚠️
14 May 2026◈ predicted · in 14 days
Predicted: ransomware adoption risk
High EPSS and SMB exposure profile suggest this CVE may be incorporated into ransomware campaigns within 14 days.
◈ Predicted eventsare estimates based on EPSS score, exploit maturity, and historical CVE progression patterns. They are not guaranteed outcomes.
Affected Products
sharepoint server
Remediation & References
⚡ CISA Required Action

Disconnect public-facing versions of SharePoint Server that have reached their end-of-life (EOL) or end-of-service (EOS) to include SharePoint Server 2013 and earlier versions. For supported versions, please follow the mitigations according to CISA (URL listed below in Notes) and vendor instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.

Federal agency patch deadline: 2025-07-21
What to do
🚨Patch immediately — actively exploited in the wildcritical

CISA has confirmed exploitation of this vulnerability. Federal agencies must patch within the KEV deadline. SMBs should treat this as P0: patch or mitigate within 24–48 hours.

🌐No authentication required — restrict external access nowhigh

This vulnerability can be exploited remotely without credentials or user interaction. Until patched: block access to the affected service from the internet using firewall rules or ACLs. Only allow access from trusted IPs.

🪟Deploy Microsoft patch via Windows Update or WSUShigh

Apply the patch from this month's Microsoft Patch Tuesday via Windows Update. For managed environments, push via WSUS or Microsoft Endpoint Manager. Prioritise servers and domain controllers over workstations.

📊High exploitation probability — EPSS 90.5%high

EPSS (Exploit Prediction Scoring System) estimates a 90.5% probability this vulnerability will be exploited in the next 30 days. This places it in the top top 10% of all CVEs by exploitation likelihood.

NVD Full Entry ↗Official vulnerability detail, CVSS vectors, CPE listCISA KEV Entry ↗CISA Known Exploited Vulnerabilities catalogEPSS Score ↗Exploit Prediction Scoring System — FIRST.orgMitre CVE ↗MITRE CVE Program official entry
Vendor & Exploit References
Scoring Methodology

SMB Attack Probability Score weights: EPSS exploit likelihood (35%), CISA KEV active exploitation (25%), SMB stack prevalence (20%), exploit maturity (10%), CVSS network vector complexity (10%). Impact scenarios are derived from software category and historical SMB incident patterns. Scores recompute daily.