CVE-2026-70306: Microsoft Office SharePoint Spoofing Vulnerability

criticalCVSS 9.3CVE-2026-70306

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network.

CSIRTS triage

vendor: Microsoft product: Microsoft Office SharePoint Cross-site scripting

What: Improper input neutralization in SharePoint allows cross-site scripting attacks that enable spoofing.
Who is affected: Users accessing affected SharePoint deployments via web browsers.
Urgency: Critical priority; network-exploitable XSS with high impact requires immediate remediation.
Action: Apply SharePoint security updates addressing CVE-2026-70306 immediately.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: critical — CVSS 9.3
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70306

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.

Low exploitation riskCVE-2026-703060.61% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 46% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-70306	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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