CVE-2026-62873Network attack vector

Unauthenticated privilege escalation via improper signature verification

Published Aug 6, 2026 · Updated Aug 25, 2026

Improper cryptographic signature verification in Microsoft 365 Admin Center allows remote attackers to elevate privileges over a network. Microsoft has not disclosed which signed data or verification path accepts an invalid signature, so the concrete validation error remains unpublished. No account or user interaction is required, and successful exploitation grants elevated privileges within the hosted admin service.

CVSS severity9.8
Critical
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper cryptographic signature verification in Microsoft 365 Admin Center allows remote attackers to elevate privileges over a network. Microsoft has not disclosed which signed data or verification path accepts an invalid signature, so the concrete validation error remains unpublished. No account or user interaction is required, and successful exploitation grants elevated privileges within the hosted admin service.

The record

CVE
CVE-2026-62873
Published
Aug 6, 2026
Updated
Aug 25, 2026
Vendor
Microsoft
Product
Microsoft 365 Admin Center
Classifications
CWE-347, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=-

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft 365 Admin Centerversion=-

Published CVSS scores

9.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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