[UPDATE] [high] Microsoft SharePoint Server 2016 and SharePoint Server 2019: Vulnerability allows code execution
A remote, authenticated attacker can exploit a vulnerability in Microsoft SharePoint Server 2016, Microsoft SharePoint Server 2019, and Microsoft SharePoint to execute arbitrary program code.
CSIRTS triage
- What
- A vulnerability allows a remote, authenticated attacker to execute arbitrary program code.
- Who is affected
- Deployments of Microsoft SharePoint Server 2016 and 2019 are affected.
- Urgency
- Remediation is high priority due to the high severity and active exploitation of the vulnerability.
- Action
- Update to the latest version of SharePoint Server to mitigate the vulnerability.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-1652
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Moderate exploitation riskCVE-2026-456593.2% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 87% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-45659 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- criticalexploitedAL26-015 - Critical vulnerability impacting Microsoft SharePoint Server – CVE-2026-45659cccs
- highexploitedCISA Adds One Known Exploited Vulnerability to Catalogcisa
- criticalexploitedCVE-2026-45659: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerabilitycisa-kev
Recent advisories for Microsoft SharePoint Server
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- criticalexploitedAL26-015 - Critical vulnerability impacting Microsoft SharePoint Server – CVE-2026-45659cccs · 2026-07-02
- criticalexploitedCVE-2026-45659: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerabilitycisa-kev · 2026-07-01
- mediumCVE-2026-45479: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
- mediumCVE-2026-45468: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
- mediumCVE-2026-45467: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
- mediumCVE-2026-45453: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
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