CVE-2026-56155

Tenable Blog · Jul 16, 2026

Four Microsoft SharePoint Server vulnerabilities are under active exploitation, prompting CISA to issue a hardening alert. An additional high-severity flaw recently patched adds pressure for organizations running on-premises deployments.Key TakeawaysCISA confirmed active exploitation of three on-premises SharePoint Server vulnerabilities (CVE-2026-32201, CVE-2026-45659, CVE-2026-56164), used to gain unauthorized access, establish remote code execution, steal IIS machine keys and deploy malware for persistence.Two additional SharePoint Server vulnerabilities disclosed on July 14, 2026, CVE-2026-55040 and CVE-2026-58644, were not yet observed exploited at the time of publication, but Microsoft has flagged CVE-2026-58644 as exploited on July 15.Microsoft released patches for all five vulnerabilities and Microsoft Defender Antivirus detection signatures are available to identify exploitation activity for three of the actively exploited flaws.BackgroundTenable's Research Special Operations (RSO) team has compiled this blog to answer Frequently Asked Questions (FAQ) regarding active exploitation of Microsoft SharePoint Server vulnerabilities.FAQWhen did CISA issue an alert about SharePoint Server exploitation?On July 14, 2026, the U.S. Cybersecurity and Infrastructure Security Agency (CISA) published an alert confirming active exploitation of three on-premises SharePoint Server vulnerabilities: CVE-2026-32201, CVE-2026-45659, and CVE-2026-56164. The alert noted that these flaws had been used to gain unauthorized access to SharePoint deployments across all supported on-premises versions and flagged two additional high-risk vulnerabilities, CVE-2026-55040 and CVE-2026-58644, as not yet exploited but warranting immediate patching. However in an update to the security advisory on July 15, Microsoft confirmed CVE-2026-58644 has been exploited in the wild.What vulnerabilities are covered in this alert?Five Microsoft SharePoint Server vulnerabilities are covered in CISA’s...

Rapid7 · Jul 14, 2026

Microsoft is publishing 622 vulnerabilities on July 2026 Patch Tuesday, including a record-breaking 416 Windows vulnerabilities. Microsoft is aware of exploitation in the wild for two of the vulnerabilities published today, both of which are listed on CISA KEV, as well as public disclosure for one other. As usual, browser vulns are not included in the Patch Tuesday count above. Rapid7 noted last month that Microsoft no longer enumerates Chromium CVEs in the Security Update Guide. However, Microsoft has now taken the pursuit of minimalism much further, since today’s Security Update Guide no longer lists out even Microsoft vulnerabilities! Instead, we now receive a summary table of vulnerability counts by product family, as well as a new slimline “Notable CVEs” section. All of this only serves to illustrate the recent industry-wide trend of exploding vulnerability report counts, with an associated uptick in the publication of remediations as a trailing indicator.SharePoint: critical auth bypass by Rapid7Today sees the publication of CVE-2026-55040, a critical authentication bypass in Microsoft SharePoint. Discovered by Rapid7 Senior Principal Security Researcher Stephen Fewer, and published today in coordination with Microsoft, this vulnerability is the first in a pair of exploits which, when chained together, can lead to unauthenticated remote code execution against a vulnerable SharePoint server. Patches are available for SharePoint Server Subscription Edition, 2019, and 2016. As the full Rapid7 blog post sets out, the second vulnerability in the full RCE chain remains embargoed for now, with Microsoft expected to publish patches for that second vulnerability as part of Patch Tuesday August 2026. Microsoft noted: “We would like to thank Rapid7 for responsibly reporting this issue through coordinated vulnerability disclosure.”SharePoint: zero-day EoPIt’s a rare Patch Tuesday which doesn’t include multiple SharePoint fixes, and today is no exception. Microsoft is...

Cisco Talos Blog · Jul 14, 2026

Microsoft has released its monthly security update for July 2026, which includes 622 vulnerabilities affecting a range of products, including 57 that Microsoft marked as "critical".Microsoft notes that two of the vulnerabilities disclosed this month have been exploited in the wild.CVE-2026-56155 is an important-

Tenable Blog · Jul 14, 2026

56Critical510Important3Moderate0LowMicrosoft addresses 569 CVEs in the largest Patch Tuesday release yet. This month’s release includes three zero-days, two of which were exploited in the wild.Microsoft patched 569 CVEs in its July 2026 Patch Tuesday release, with 56 rated critical, 510 rated as important, and 3 rated as moderate. This marks the largest Patch Tuesday release ever, crushing the previous record of 198 CVEs in June. Last week, Microsoft announced that its multi-model agentic scanning harness (MDASH) is being used to identify vulnerabilities faster and noted that “customers will see a higher volume of security updates included in each security release.”This month’s update includes patches for:.NET.NET Core.NET FrameworkASP.NET CoreActive Directory Certificate Services (AD CS)Active Directory Domain ServicesActive Directory Federation Services (AD FS)Azure Active DirectoryAzure CycleCloudAzure Monitor AgentAzure Spring AppsCode Integrity DLL (ci.dll)Composite Image File System DriverContent Delivery ManagerDesktop Window ManagerExtensible Storage Engine (ESENT)GitHub Copilot and Visual StudioGitHub Copilot and Visual Studio CodeGithub CopilotHTTP/2Microsoft 365 Copilot for iOSMicrosoft Bing App for IOSMicrosoft CopilotMicrosoft DefenderMicrosoft Defender for EndpointMicrosoft Dynamics NAVMicrosoft Edge for AndroidMicrosoft Exchange ServerMicrosoft Fabric Data WarehouseMicrosoft Graphics ComponentMicrosoft Input Method Editor (IME)Microsoft Install ServiceMicrosoft NAT Helper Components (ipnathlp.dll)Microsoft OfficeMicrosoft Office ExcelMicrosoft Office OneNoteMicrosoft Office PowerPointMicrosoft Office SharePointMicrosoft Office WordMicrosoft Printer DriversMicrosoft SurfaceMicrosoft WindowsMicrosoft Windows App StoreMicrosoft Windows Codecs LibraryMicrosoft Windows Media FoundationMicrosoft Windows Search ComponentMicrosoft Windows SpeechMicrosoft XMLMicrosoft XML Core ServicesMinecraft Bedrock Dedicated ServerOutlook CopilotPower BIQuality Windows...

All CISA Advisories · Jul 14, 2026

CISA has added four new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation. CVE-2026-15409 SonicWall SMA1000 Appliances Server-Side Request Forgery Vulnerability CVE-2026-15410 SonicWall SMA1000 Appliances Code Injection Vulnerability CVE-2026-56155 Microsoft Active Directory Federation Services Insufficient Granularity of Access Control Vulnerability CVE-2026-56164 Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability These types of vulnerabilities are a frequent attack vector for malicious cyber actors and pose significant risks to the federal enterprise. Binding Operational Directive (BOD) 26-04: Prioritizing Security Updates Based on Risk establishes vulnerability management requirements for Federal Civilian Executive Branch (FCEB) agencies. BOD 26-04 reinforces the importance of the KEV Catalog and requires federal agencies to prioritize rapid remediation of high-risk vulnerabilities, specifically those identified by Common Vulnerabilities and Exposures (CVEs) listed in CISA’s KEV Catalog on publicly exposed assets that grant total control of the asset post-exploitation, while deferring action for lower-risk vulnerabilities. BOD 26-04 further establishes basic expectations for when agencies must check whether threat actors compromised the system before the patch was applied. While BOD 26-04 applies only to FCEB agencies, CISA encourages all organizations to adopt risk-based vulnerability management and prioritize remediation of KEV Catalog vulnerabilities. CISA will continue to add vulnerabilities to the catalog that meet the specified criteria. Aware of an exploited vulnerability not currently listed in the KEV Catalog? Submit it for potential addition through CISA’s KEV Nomination Form. Potential KEV additions must have a CVE ID, evidence of exploitation, and clear mitigation guidance.