Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-66822Unknown / EvaluatingImportant (raw)CVSS 5.9CWE-201
.NET Information Disclosure Vulnerability
Published: 13 Oct 2026•Last updated: 15 Oct 2026, 12:30 PM IST•Source identifier: secure@microsoft.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
5.9Important (raw)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.7%0.007
Percentile51st
Weakness type
CWE-201
No further CWE recorded
Remediation
Patch status unknown
KB5130036, KB5130034, KB5130035
Why It Matters
Analysis dossierWhy It Matters
Insertion of sensitive information into sent data in .NET 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
14 source-backed productsAffected products and versions (source)
- .NET 11.0 installed on Windows · version range not provided by source · Microsoft MSRC · Source
- .NET 11.0 installed on Linux · version range not provided by source · Microsoft MSRC · Source
- .NET 11.0 installed on Mac OS · version range not provided by source · Microsoft MSRC · Source
- .NET 10.0 installed on Windows · version range not provided by source · Microsoft MSRC · Source
- .NET 10.0 installed on Linux · version range not provided by source · Microsoft MSRC · Source
- .NET 10.0 installed on Mac OS · version range not provided by source · Microsoft MSRC · Source
- .NET 8.0 installed on Linux · version range not provided by source · Microsoft MSRC · Source
- .NET 8.0 installed on Windows · version range not provided by source · Microsoft MSRC · Source
- .NET 8.0 installed on Mac OS · version range not provided by source · Microsoft MSRC · Source
- .NET 9.0 installed on Linux · version range not provided by source · Microsoft MSRC · Source
- .NET 9.0 installed on Mac OS · version range not provided by source · Microsoft MSRC · Source
- Microsoft Visual Studio 2022 version 17.14 · version range not provided by source · Microsoft MSRC · Source
- .NET 9.0 installed on Windows · version range not provided by source · Microsoft MSRC · Source
- Microsoft Visual Studio 2026 version 18.10 · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBKB5130036, KB5130034, KB5130035
Vendor or catalog guidance (source)
- Microsoft MSRC: Release Notes
- Microsoft MSRC: Install the security update KB5130036 listed by MSRC
- Microsoft MSRC: Install the security update KB5130034 listed by MSRC
- Microsoft MSRC: Install the security update KB5130035 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: .NET 11.0 installed on Windows, Vendor: Microsoft); network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)
Exposure
- Identify affected Microsoft products and compare local builds with the MSRC advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · The MSRC product/build mapping establishes applicability. · Rule microsoft-enterprise
- 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
- 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
- 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
- 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 · Unknown
- CPE
- Unknown
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-2026-66822
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-66822
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-66822"| 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.