SecOps SignalSecurity Intelligence Workspace
Collection Degraded30 / 46 Sources HealthyPublic Intel Only
Vulnerabilities/CVE-2026-77900Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-77900Unknown / EvaluatingCritical (raw)CVSS 9.8CWE-306

Azure App Service Remote Code Execution Vulnerability

Published: 08 Oct 2026•Last updated: 08 Oct 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.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
9.8Critical (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.5%0.005
Percentile41st
Weakness type
CWE-306
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

Missing authentication for critical function in Azure App Service allows an unauthorized attacker to execute code over a network.

SOC priority

High Severity / Review

Actively exploited

No

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; CRITICAL severity; Critical CVSS without confirmed KEV exploitation

Affected Products & Remediation

1 source-backed product
Affected products and versions (source)
  • Azure App Service for Linux · 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 authentication-weakness (CWE-306); network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)

Exposure

  1. Identify affected authentication surfaces and compare versions with the advisory.Telemetry: Application inventory · A CWE match is not proof of local exposure. · Rule authentication-weakness
  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 unexpected successful sign-ins and changes to privileged accounts on affected systems.Telemetry: SigninLogs · Access anomalies are relevant to authentication weaknesses. · Rule authentication-weakness
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. Verify the vendor fix and review privileged access after remediation.Telemetry: Identity audit logs · Post-change review checks the response. · Rule authentication-weakness

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

3 public sources
api.msrc.microsoft.comSource recordnvd.nist.govSource recordmsrc.microsoft.comSource 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-2026-77900
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-77900
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-77900"| 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

Microsoft Security Update Guide · Limited verificationOctober 2026 Security UpdatesPublished 13 Oct 2026
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.