Targets widely deployed Microsoft SharePoint; authenticated RCE can lead to full server compromise and enterprise disruption.
CVE-2026-70321
Authenticated deserialization RCE in Microsoft SharePoint allows remote code execution.
Is CVE-2026-70321 being exploited?
Not confirmed. CVE-2026-70321 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 1.3% probability of exploitation in the next 30 days.
How severe is CVE-2026-70321?
CVE-2026-70321 is rated High with a CVSS score of 8.8. 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-2026-70321?
Yes. A fix has been recorded for CVE-2026-70321. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-70321 affect?
CVE-2026-70321 affects Microsoft Office SharePoint (on-premises). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-70321?
Apply vendor update immediately; restrict SharePoint access and monitor logs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated remote code execution on SharePoint servers, enabling arbitrary code execution and potential full server compromise.
Immediate action required
- 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.