Threat Intelligence / CVE / CVE-2025-53770

CVE-2025-53770 — Microsoft Sharepoint Server

CISA KEVRansomware
CVSS v3.1 9.8 (CRITICAL) · EPSS 89.9% (higher than 99.5% of all scored CVEs) · Priority 10/10 · Published 2025-07-20

As of 2025-10-27, CVE-2025-53770 is a CRITICAL-severity vulnerability in Microsoft Sharepoint Server, CVSS v3.1 9.8, EPSS 89.9% (99.5th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-07-20), with a US federal remediation deadline of 2025-07-21, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 4 tracked threat campaigns to CVE-2025-53770, most recently “CVE-2026-56164: Microsoft SharePoint Server Missing-Authentication Vulnerability Actively Exploited, Added to CISA KEV”.

Last updated: 2025-10-27

What is 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 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.

The record classifies CVE-2025-53770 under weakness class CWE-502. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 3 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 419 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST)
89.9% probability of exploitation in the next 30 days, higher than 99.5% of all scored CVEs
CISA KEV
Listed since 2025-07-20, federal remediation deadline 2025-07-21 — used in known ransomware campaigns
Threadlinqs priority
10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published
2025-07-20, last modified 2025-10-27

Is CVE-2025-53770 being exploited?

CISA added CVE-2025-53770 to the Known Exploited Vulnerabilities catalog on 2025-07-20, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2025-07-21 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2025-53770

Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770. Because CVE-2025-53770 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2025-07-21. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2025-53770

4 tracked threats in the Threadlinqs corpus reference CVE-2025-53770, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2025-53770 are available via the Threadlinqs MCP server (Purple tier). View plans →

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