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CISA Urges SharePoint Hardening After New Exploitations ↗ source

July 14, 2026 CISA Alert

Summary

CISA has updated this Alert to clarify guidance on avoiding the direct exposure of SharePoint Servers to the internet. CISA has updated this Alert to reflect the addition of CVE-2026-55040 to its Known Exploited Vulnerabilities (KEV) Catalog on August 18, 2026. CISA has updated this Alert to include CVE-2026-50522 and its addition to the KEV Catalog on July 22, 2026. CISA has updated this Alert to reflect the addition of CVE-2026-58644 to its KEV Catalog on July 16, 2026. CISA is aware of active exploitation of vulnerabilities CVE-2026-32201 , CVE-2026-45659 , CVE-2026-56164 , CVE-2026-58644 , CVE-2026-50522 , and CVE-2026-55040 , enabling cyber threat actors to gain unauthorized access to on-premises SharePoint Server instances. These vulnerabilities affect all supported on-premises SharePoint Server versions (Subscription Edition, 2019, and 2016) and involve establishing remote code execution (RCE) and post-exploitation activities, such as stealing Internet Information Services (IIS) machine keys and performing deserialization techniques, to gain persistence and deploy malware.

News Coverage

Articles from the monitored vendor research blogs and security news feeds that reference a CVE cited in this publication, or name the campaign it covers. Coverage begins when feed monitoring started; earlier articles are not indexed.

CVEs Referenced in This Publication

CVECVSSAffected
CVE-2026-50522 9.8 Critical Microsoft SharePoint Microsoft SharePoint contains a deserialization of untrusted data vulnerability which could allow an unauthorized attacker to execute code over a net…
CVE-2026-58644 9.8 Critical Microsoft SharePoint Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.
CVE-2026-55040 9.1 Critical Microsoft SharePoint Microsoft SharePoint contains a weak authentication vulnerability which allows an unauthorized attacker to bypass a security feature over a network.
CVE-2026-45659 8.8 High Microsoft SharePoint Server Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a net…
CVE-2026-32201 6.5 Medium Microsoft SharePoint Server Microsoft SharePoint Server contains an improper input validation vulnerability that allows an unauthorized attacker to perform spoofing over a netwo…
CVE-2026-56164 5.3 Medium Microsoft SharePoint Server Microsoft SharePoint contains a missing authentication for critical function vulnerability that allows an unauthorized attacker to elevate privileges…

Extracted from the publication text. Each CVE links to its tracked detail page.

Vendors Named in This Publication

Each vendor links to its Known Exploited Vulnerabilities catalog page. Only vendors that appear in the KEV catalog are listed, either because the publication cites one of their KEV entries or because it names them directly.