U.S. CISA urges FCEB agencies to fix two Microsoft SharePoint flaws immediately and added them to its Known Exploited Vulnerabilities catalog
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2025-49704 +1 in the same advisory: …49706 | Authenticated Code Injection RCE in Microsoft SharePoint CVE-2025-49704 is a code injection vulnerability (CWE-94) in Microsoft SharePoint that allows an authorized (authenticated) attacker to execute arbitrary code on the server over the network, by sending requests whose attacker-controlled input SharePoint executes as code. It can be chained with CVE-2025-49706, and Microsoft subsequently issued CVE-2025-53770 as a patch bypass of the original CVE-2025-49704 fix, meaning the CVE-2025-53770 updates provide stronger protection and should be treated as the definitive remediation. Successful exploitation yields remote code execution on the SharePoint server, and CISA added the flaw to the KEV on 2025-07-22 with known ransomware use. Organizations running on-premises SharePoint Server are affected; CISA directs owners of public-facing servers running EOL/EOS versions (SharePoint Server 2013 and earlier) to disconnect them, and operators of supported versions to apply the CISA and vendor mitigations and updates, with cloud SharePoint services governed by BOD 22-01. Exploitation is confirmed in the wild and EPSS assigns a 100% probability of exploitation within 30 days (top percentile), although no public proof-of-concept code is documented. Do: Apply Microsoft's SharePoint Server updates for CVE-2025-53770, which supersede the original CVE-2025-49704 fixes with more robust protection, prioritizing internet-facing servers. Disconnect public-facing SharePoint servers running EOL/EOS versions (SharePoint Server 2013 and earlier), and for supported versions follow the CISA and vendor mitigations, with cloud services handled per BOD 22-01. Because in-the-wild exploitation and ransomware use are confirmed, hunt for indicators of compromise and ransomware activity on exposed SharePoint servers. | 8.8 group max | 100% | KEV ransomware |
| masstens of thousands of internet-exposed SharePoint servers per public scans, within a total on-premises install base plausibly exceeding 100,000 deployments… | |
| CVE-2025-53770 | Unauthenticated Deserialization RCE in Microsoft SharePoint Server on-premises CVE-2025-53770 is a deserialization of untrusted data vulnerability (CWE-502) in Microsoft SharePoint Server on-premises that allows an unauthorized attacker to execute code over a network. It is triggered when the server deserializes attacker-controlled data, can be chained with CVE-2025-53771, and it bypasses the fixes issued for CVE-2025-49704, meaning the earlier patches are insufficient. Successful exploitation yields remote code execution on the SharePoint server, and ransomware operators are known to be using it. Any organization running SharePoint Server on-premises is affected, particularly internet-facing deployments and end-of-life versions such as SharePoint Server 2013 and earlier that can no longer be patched. The flaw is being actively exploited — it was added to CISA's KEV on 2025-07-20 with known ransomware use — and EPSS assigns it a 100% probability of exploitation within 30 days. Do: Apply Microsoft's updated SharePoint Server security updates that fix CVE-2025-53770 — these include more robust protection than the earlier CVE-2025-49704 updates — and ensure the companion CVE-2025-53771 is also addressed, following CISA and vendor mitigation instructions for supported versions. Disconnect public-facing SharePoint Server 2013 or earlier (EOL/EOS) instances, minimize internet exposure of supported servers, and hunt for signs of compromise given the known ransomware exploitation. | 9.8 | 100% | KEV ransomware PoC ×3 |
| mass≈25,000–100,000 internet-exposed on-premises SharePoint servers (public internet-wide scans); total on-prem installed base plausibly >1M users |
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U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds two Microsoft SharePoint flaws to its Known Exploited Vulnerabilities catalog.
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added two Microsoft SharePoint flaws to its Known Exploited Vulnerabilities (KEV) catalog.
Below are the descriptions for these flaws:
- CVE-2025-49704 Microsoft SharePoint Code Injection Vulnerability
- CVE-2025-49706 Microsoft SharePoint Improper Authentication Vulnerability
This week, Microsoft warned of a SharePoint zero-day vulnerability, tracked as CVE-2025-53770 (CVSS score of 9.8), which is under active exploitation. The vulnerability is a deserialization of untrusted data in on-premises Microsoft SharePoint Server, an unauthorized attacker could exploit the vulnerability to execute code over a network. The flaw was discovered by Viettel Cyber Security via Trend Micro’s ZDI.
Microsoft states that the vulnerability CVE-2025-53770 is a variant of a spoofing flaw tracked as CVE-2025-49706 (CVSS score: 6.3), which the IT giant addressed with the release of July 2025 Patch Tuesday updates.
Security researchers from Eye Security and Palo Alto Networks warned of attacks combining two SharePoint flaws, CVE-2025-49706 and CVE-2025-49704, in a chain called “ToolShell.”
These bugs allow attackers to bypass authentication and run code remotely on vulnerable SharePoint servers. However, given that CVE-2025-53770 is a variant of CVE-2025-49706, the attacks are likely related.
Between July 17 and 19, 2025, SentinelOne researchers observed three distinct ToolShell exploitation waves, each with unique methods and goals:
First Wave (July 18):
From IP 107.191.58[.]76, attackers used PowerShell to deploy a base64-decoded payload (spinstall0.aspx) to the SharePoint LAYOUTS directory. This webshell wasn’t used for command execution but harvested MachineKey values—critical for forging authentication tokens and maintaining access in load-balanced environments.
Second Wave (July 19):
From IP 104.238.159[.]149, attackers repeated the same payload deployment, altering the directory path to target a different SharePoint version. Again, spinstall0.aspx extracted cryptographic secrets for persistence, not command execution.
“No Shell” Cluster (July 17–18):
From IP 96.9.125[.]147, this earliest and stealthiest wave used in-memory .NET module execution without writing files to disk. Attackers delivered encoded payloads and executed them dynamically via PowerShell or .NET reflection, making detection difficult. This fileless approach suggests a highly skilled red team or nation-state actor focused on stealth and credential harvesting.
All clusters targeted high-value SharePoint deployments, with a clear emphasis on persistence and access via cryptographic key theft, rather than immediate system control.
While SentinelOne did not attribute the attack to a specific threat actor, The Washington Post, citing its source, reported that the attacks targeted SharePoint servers were likely conducted by unnamed China-linked threat actors.
According to Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities, FCEB agencies have to address the identified vulnerabilities by the due date to protect their networks against attacks exploiting the flaws in the catalog.
Experts also recommend that private organizations review the Catalog and address the vulnerabilities in their infrastructure.
CISA orders federal agencies to fix the vulnerabilities by July 23, 2025.
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