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Vulnerabilities/CVE-2026-69378Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-69378Unknown / EvaluatingImportant (raw)CVSS 7.5

Microsoft Exchange Server Denial of Service Vulnerability

Published: 08 Sept 2026•Last updated: 08 Sept 2026, 12:30 PM IST•Source identifier: Unknown
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
7.5Important (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
1.2%0.012
Percentile67th
Weakness type
—
No further CWE recorded
Remediation
Patch status unknown
KB5121611, KB5121610, KB5121608, KB5121609

Why It Matters

Analysis dossier

Why It Matters

Uncontrolled recursion in Microsoft Exchange Server allows an unauthorized attacker to deny service over a network.

SOC priority

Medium

Actively exploited

No

Publicly disclosed

Unknown

Risk basis: No confirmed exploitation signal in current enrichment

Affected Products & Remediation

4 source-backed products
Affected products and versions (source)
  • Microsoft Exchange Server 2016 Cumulative Update 23 · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Exchange Server 2019 Cumulative Update 14 · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Exchange Server Subscription Edition RTM · version range not provided by source · Microsoft MSRC · Source
  • Microsoft Exchange Server 2019 Cumulative Update 15 · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBKB5121611, KB5121610, KB5121608, KB5121609

Vendor or catalog guidance (source)

  • Microsoft MSRC: Install the security update KB5121611 listed by MSRC
  • Microsoft MSRC: Install the security update KB5121610 listed by MSRC
  • Microsoft MSRC: Install the security update KB5121608 listed by MSRC
  • Microsoft MSRC: Install the security update KB5121609 listed by MSRC

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
No
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched microsoft-enterprise (Affected product: Microsoft Exchange Server 2016 Cumulative Update 23, Vendor: Microsoft); network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)

Exposure

  1. Identify affected Microsoft products and compare local builds with the MSRC advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · The MSRC product/build mapping establishes applicability. · Rule microsoft-enterprise
  2. Identify devices reporting this CVE and note which expose the affected service to untrusted networks.Telemetry: DeviceTvmSoftwareVulnerabilities · A network-reachable, no-privilege vector makes internet-facing instances the first exposure question. · Rule network-unauthenticated

Exploitation evidence

  1. Review the advisory's documented behavior on matching hosts before selecting a hunt.Telemetry: DeviceProcessEvents · Product family alone does not justify a CVE-specific detection. · Rule microsoft-enterprise
Show more (2)

Exploitation evidence

  1. Review inbound connections to the affected service from unexpected sources since the advisory date.Telemetry: DeviceNetworkEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule network-unauthenticated

Response

  1. Confirm the source-stated KB or mitigation on matching assets.Telemetry: DeviceTvmSoftwareVulnerabilities · A post-update inventory check verifies remediation. · Rule microsoft-enterprise

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
Unknown
Record status · verification
UPDATED · Unknown
CPE
Unknown

Evidence & Provenance

1 public source
api.msrc.microsoft.comSource record
Detection Hunting Query

— No published hunting query names this record. Browse community and library queries instead.

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Correlated briefings

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.