CVE-2026-83947: Microsoft Azure Event Grid System

Azure Event Grid Spoofing Vulnerability

CVSS 7.7 HighEPSS 0.0053 · 45th percentile

Published by the CVE Program (CNA: microsoft) at 8 Oct 2026, 22:15 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
Microsoft	Azure Event Grid System	affected -

Identifiers

CVE-2026-83947

CNA

microsoft

Weakness (CWE)

CWE-862

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Microsoft Azure Event Grid is affected by a spoofing vulnerability caused by missing authorization. An authorized attacker with network access can perform spoofing against the service. The source gives few details, and no fixed versions or workaround are listed.

Written 11 Nov 2026.

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.7	High	3.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N/E:U/RL:O/RC:C	CNA (microsoft)

CISA KEV Not listed.
EPSS 0.0053, the 45th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

8 Oct 2026, 22:15 UTC Confirmed by the CVE List
31 Oct 2026, 16:31 UTC First seen by agentprime

Sources

References from the CNA

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83947 vendor-advisorypatch

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.