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Vulnerabilities/CVE-2026-55005Public Intelligence Dossier
Source: microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-55005Unknown / EvaluatingHIGH (raw)CVSS 8.8CWE-122

Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.

Published: 14 Jul 2026•Last updated: 15 Oct 2026, 03:40 AM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
8.8HIGH (raw)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Metric sourcesecure@microsoft.com
EPSS probability
1%0.010
Percentile63rd
Weakness type
CWE-122
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.

SOC priority

High

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

2 source-backed products
Affected products and versions (source)
  • microsoft exchange server · 2016; 2019; subscription edition < 15.02.2562.045 · NVD CPE · Source
  • microsoft exchange server subscription edition · < 15.02.2562.045 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

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)
Unknown
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, Vendor: microsoft)

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

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

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
secure@microsoft.com
Record status · verification
UPDATED · Microsoft primary source linked
CPE
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_23:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_14:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_15:*:*:*:*:*:*, cpe:2.3:a:microsoft:exchange_server_subscription_edition:*:*:*:*:*:*:*:*

Evidence & Provenance

2 public sources
msrc.microsoft.comSource recordnvd.nist.govSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2026-55005
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-55005
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-55005"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

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.