Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-55946Unknown / EvaluatingCritical (raw)CVSS 6.1CWE-77
Microsoft Copilot Information Disclosure Vulnerability
Published: 17 Sept 2026•Last updated: 17 Sept 2026, 12:30 PM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
6.1Critical (raw)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.4%0.004
Percentile31st
Weakness type
CWE-77
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded
Why It Matters
Analysis dossierWhy It Matters
Ai command injection in Microsoft Copilot allows an unauthorized attacker to disclose information over a network.
SOC priority
Review
Actively exploited
No
Publicly disclosed
Unknown
Risk basis: Microsoft or Microsoft-managed product relevance
Affected Products & Remediation
1 source-backed productAffected products and versions (source)
- Microsoft Copilot · version range not provided by source · Microsoft MSRC · 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)
- 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 user-interaction-client (CVSS AV:N, CVSS UI:R)
Exposure
- Identify endpoints reporting this CVE, especially those used for email and web browsing.Telemetry: DeviceTvmSoftwareVulnerabilities · A network vector that needs user interaction points at user-facing client software. · Rule user-interaction-client
Exploitation evidence
- Review unusual child processes started by the affected client application on affected endpoints.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule user-interaction-client
Response
- Confirm the source-stated update on affected endpoints.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies remediation. · Rule user-interaction-client
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 · Unknown
- CPE
- cpe:2.3:a:microsoft:copilot:-:*:*:*:*:*:*:*
Evidence & Provenance
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-2026-55946
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-55946
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-55946"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel descSchema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
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.