CVE-2026-62911Network attack vector

Authenticated privilege escalation via capture-replay

Published Aug 11, 2026 · Updated Aug 25, 2026

Authentication bypass in Microsoft Exchange Server 2016 and 2019 and Subscription Edition allows remote authenticated users to elevate privileges via capture-replay. Microsoft has not published the Exchange component that accepts previously captured authentication material, so the public mechanism is limited to replay-based authentication acceptance. Exploitation requires valid access and user interaction per the published CVSS vector, and public records describe privilege escalation but not code execution or service interruption.

CVSS severity8.0
High
EPSS probability1.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Microsoft Exchange Server 2016 and 2019 and Subscription Edition allows remote authenticated users to elevate privileges via capture-replay. Microsoft has not published the Exchange component that accepts previously captured authentication material, so the public mechanism is limited to replay-based authentication acceptance. Exploitation requires valid access and user interaction per the published CVSS vector, and public records describe privilege escalation but not code execution or service interruption.

The record

CVE
CVE-2026-62911
Published
Aug 11, 2026
Updated
Aug 25, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-294, T1550
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 11, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.0NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-294Authentication Bypass by Capture-replay
T1550Use Alternate Authentication Material

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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