Microsoft SharePoint is widely used enterprise collaboration software; authenticated RCE could disrupt data, workloads, and services across organizations.
CVE-2026-65658
Authenticated deserialization flaw in Microsoft SharePoint enables remote code execution.
Is CVE-2026-65658 being exploited?
Not confirmed. CVE-2026-65658 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 1.4% probability of exploitation in the next 30 days.
How severe is CVE-2026-65658?
CVE-2026-65658 is rated High. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-65658?
Yes. A fix has been recorded for CVE-2026-65658. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-65658 affect?
CVE-2026-65658 affects Microsoft SharePoint Server, Office SharePoint / SharePoint components. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-65658?
Apply vendor patch/mitigations immediately; restrict admin access and isolate SharePoint from untrusted networks.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated RCE via deserialization; attacker can execute arbitrary code as SharePoint service account, access/modify data, anddeploy malware.
Immediate action required
- affected>= 16.0.0 and < 16.0.5565.1001
- affected>= 16.0.0 and < 16.0.10417.20198
- affected>= 16.0.0 and < 16.0.19725.20522
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.