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Microsoft Copilot Web CVE-2026-24301

| EUVDEUVD-2026-60762 HIGH
Command Injection (CWE-77)
2026-08-18 microsoft GHSA-9q66-w589-xv8x
7.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Send crafted request to Copilot Web endpoint
  2. Delivery
    Inject command delimiters in user-controlled input
  3. Exploit
    Input reaches unsanitized command execution path
  4. Execution
    Server executes command in constrained context
  5. Impact
    Sensitive data returned to attacker

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Command injection prevention
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

No authentication is required per CVSS PR:N - the attack targets Copilot Web as an unauthenticated, publicly accessible network service. The SSVC Automatable=no determination implies at least one step impedes fully automated mass exploitation, possibly rate limiting, AI-model-mediated parsing behavior that introduces non-determinism, or implicit session handling not reflected in the CVSS PR:N rating. The impact is confined to confidentiality only; the injection context does not appear to permit write operations, code execution beyond the constrained environment, or availability disruption. No specific non-default configuration requirement is stated in the description.

Impact

The CVSS 7.5 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) positions this as an unauthenticated, low-complexity network-exploitable information disclosure with high confidentiality impact. However, SSVC introduces meaningful friction: Automatable=no directly conflicts with the AC:L/PR:N/UI:N CVSS metrics and implies a non-automatable step - likely rate limiting, session-tied behavior inherent to Copilot's AI interface, or a CAPTCHA-equivalent - that is not reflected in the base vector. EPSS at 1.63% (74th percentile) and SSVC Exploitation=none confirm the vulnerability has not been observed as actively exploited despite the public GitHub gist PoC. The impact ceiling of C:H with no integrity or availability consequence limits overall blast radius. This warrants prompt patching given the public PoC, but is not an emergency-severity incident absent evidence of active exploitation.

Exploit ScenarioDerived

An unauthenticated attacker submits a crafted HTTP request to a publicly accessible Microsoft Copilot Web endpoint, embedding command-injection payloads in a user-controlled input field such as a prompt or query parameter. The server processes the input through an insufficiently sanitized command execution path, returning sensitive system or application data in the response. A proof-of-concept demonstrating this technique is publicly available at the GitHub gist referenced in the advisory.

Monitor Track and reassess. Why: Vendor states no customer action required.
1 PoC candidate (unverified) Patch available 1.6% exploitation probability (EPSS)

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AnalysisAIv2 – Sep 10, 2026

Command injection in Microsoft Copilot Web (copilot_web) enables unauthenticated remote attackers to exfiltrate sensitive data over the network by embedding malicious command elements in user-controlled input. The impact is strictly bounded to confidentiality - no integrity or availability loss - and a proof-of-concept is publicly available on GitHub. Despite a CVSS 7.5 score and public PoC, SSVC classifies exploitation as none with Automatable=no, and EPSS sits at 1.63%, suggesting limited real-world exploitation activity at time of analysis.

Earlier versions of this analysis (1)
v1 Aug 18, 2026 - 14:01 CVSS 8.8

Command injection (CWE-77) in Microsoft Copilot Web enables a remote unauthenticated attacker to achieve high-impact information disclosure - and potentially broader compromise - by inducing a victim user to submit specially crafted input through the web interface. The CVSS base score of 8.8 reflects High impacts across confidentiality, integrity, and availability, though the official CVE description scopes the primary disclosed impact to information disclosure only; this discrepancy is consistent with command injection primitives typically enabling full execution-layer access regardless of the stated primary impact. No public exploit code has been identified (temporal metric E:U) and an official vendor fix is available via the Microsoft Security Response Center.

RemediationAI

Microsoft has released a patch per the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-24301. Because Copilot Web is a Microsoft-hosted SaaS product, the fix is applied server-side by Microsoft without requiring end-user patching action; organizations should confirm their tenant is routing through Microsoft's updated backend. As a compensating control during any transition window, restricting Copilot Web access to authenticated corporate identities via Azure AD Conditional Access policies would effectively eliminate the PR:N attack surface, though this removes any unauthenticated or guest-access use cases. No exact patched version number is independently confirmable from the available data.

Affected VersionsENISA

Copilot Web - (version not specified)

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-77 (Improper Neutralization of Special Elements used in a Command) identifies a command injection root cause in the Microsoft Copilot Web application, confirmed by CPE cpe:2.3:a:microsoft:copilot_web:*. Command injection arises when attacker-controlled input containing shell metacharacters or command delimiters reaches an underlying command interpreter without adequate sanitization. The impact being strictly confidentiality-only (C:H/I:N/A:N) suggests the execution context is constrained - the injectable surface likely feeds a read-only subsystem, sandboxed process, or AI-mediated pipeline that returns data but does not permit write or execution primitives beyond the disclosed information.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY HIGH
NVD 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
vuln.today AI 7.5 HIGH

Unauthenticated network-reachable SaaS endpoint; impact confined strictly to confidentiality with no write or availability primitives confirmed.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

3
Analysis Updated
Sep 10, 2026 - 18:43 vuln.today
v2 - CVSS changed
CVSS changed
Sep 10, 2026 - 18:37 NVD
8.8 (HIGH) 7.5 (HIGH)
CVE Published
Aug 18, 2026 - 13:19 cve.org
HIGH 8.8

DescriptionNVD

Improper neutralization of special elements used in a command ('command injection') in Microsoft Copilot allows an unauthorized attacker to disclose information over a network.

Latest POC

1 PoC candidate from github (unverified)

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Executive ViewAI

Why It Matters

Microsoft Copilot Web contains an unauthenticated command-injection vulnerability that allows remote attackers to exfiltrate sensitive organizational data without requiring credentials or user interaction. Although exploitation probability remains low at 1.6% (EPSS), publicly available proof-of-concept code combined with Copilot Web's broad deployment across enterprises creates significant confidentiality risk and potential regulatory exposure if user or operational data is compromised.

Business Impact: High
Compensating Controls

Apply vendor patch.

Threat Intelligence Overview

EPSS Score
1.6%
Top 26% exploitable
Prevalence
High
Microsoft Copilot widely deployed across enterprise Microsoft 365 tenants globally
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:N/A
Service Type
Hosted
Vendor-managed, no client patch needed
Data Quality
8 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 1.6%
Patch available Yes
Active threat No
Deciding rule
Vendor states no customer action required
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Partial

Priority Score

60
Low Medium High Critical
KEV: 0
EPSS: +2
CVSS: +38
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

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