Security Bulletin

Copilot RCE, Entra SSRF, and SharePoint Zero-Day: Critical Vulnerabilities in Microsoft’s July 2026 Advisory

3 min read Updated

AI assistants are quietly becoming one of Microsoft’s largest attack surfaces. In its July 2026 advisory, Microsoft patched a command injection vulnerability in Copilot. Crafted prompts can trigger unintended actions through this flaw. The advisory also included a critical SSRF vulnerability in Entra’s identity provisioning service. It carries the among the highest severity score in the entire release. Both point to the same shift. As AI gets embedded deeper into identity and productivity tools, the paths attackers can exploit are expanding well beyond the browser or the network perimeter.

Equally critical is a zero day vulnerability in SharePoint Server (CVE-2026-56164). It lets an unauthenticated attacker seize Farm Administrator access with no credentials at all. This is part of Microsoft’s largest Patch Tuesday on record. Over 570 vulnerabilities were patched, and two zero-days were already under active exploitation.

CVE-2026-48561 — Microsoft Copilot Remote Code Execution via Command Injection

Risk Analysis

Severity CRITICAL
CVSS v3.1 Score 9.6
Exploitation Complexity Low, but requires user interaction (victim must visit a malicious website)
Exploit Publicly Available No public PoC; exploit code maturity rated “Unproven”
Active Exploitation No
Attack Vector Network-based; unauthenticated attacker, but requires the victim to visit an attacker-controlled website that causes Microsoft Edge for Android to send crafted prompts to Copilot

CVE-2026-48561 is a critical command injection vulnerability (CWE-77) in Microsoft Copilot, carrying a CVSS score of 9.6. Unlike the SharePoint vulnerability, exploitation requires user interaction: an attacker hosts a malicious website that causes Microsoft Edge for Android to send crafted prompts to Copilot automatically when a user visits the page, without confirmation or origin validation. Microsoft has named Microsoft 365 Copilot for iOS and Android as affected products. As of publication, Microsoft assesses exploitation as “less likely” and has not detected active exploitation in the wild, a meaningfully different risk profile from the SharePoint zero-day.

CVE-2026-57100 — Microsoft Entra Provisioning Service Elevation of Privilege (SSRF)

Risk Analysis

Severity CRITICAL
CVSS v3.1 Score 9.9
Exploitation Complexity Low
Exploit Publicly Available No public PoC
Active Exploitation No
Attack Vector Network-based; attacker must already hold low-level authorization (PR:L), no user interaction required. Fixed entirely server-side by Microsoft, no customer-deployed patch exists

CVE-2026-57100 is a server-side request forgery vulnerability in the Microsoft Entra Provisioning Service (SyncFabric component), carrying the highest CVSS score in this advisory at 9.9. It allows an attacker who already holds low-level authorization to elevate privileges over the network, requiring no user interaction.

CVE-2026-56164 — SharePoint Server Unauthenticated Elevation of Privilege

Risk Analysis

Severity CRITICAL
CVSS v3.1 Score 9.8
Exploitation Complexity Low
Exploit Publicly Available No public PoC
Active Exploitation Yes (Microsoft confirmed; CISA KEV)
Attack Vector Unauthenticated, network-based HTTP request

CVE-2026-56164 is an unauthenticated elevation-of-privilege vulnerability in SharePoint Server’s client service endpoint (/_vti_bin/client.svc), caused by missing authentication (CWE-306) inside the Microsoft.Office.Server.UserProfiles assembly. It lets an attacker with no credentials and no user interaction escalate to Farm Administrator access over the network, with a CVSS score of 9.8. Microsoft confirmed active exploitation, CISA added it to the Known Exploited Vulnerabilities catalog on July 1, 2026, thirteen days before the patch shipped, and it affects on-premises SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition (SharePoint Online is not affected).

How AppTrana Protects Against July 2026 Advisory Vulnerabilities

AppTrana customers get protection against multiple critical vulnerabilities from this advisory from day zero, without waiting on internal patch cycles. For the actively exploited SharePoint zero-day (CVE-2026-56164), AppTrana identifies and blocks malicious requests targeting the vulnerable /_vti_bin/client.svc endpoint. Coverage also extends to command injection patterns relevant to the Copilot RCE vulnerability and SSRF detection relevant to the Entra provisioning vulnerability, among others detailed below.

Other July 2026 Advisory Vulnerabilities and AppTrana Coverage

In addition to the vulnerabilities covered above, AppTrana has coverage for other serious vulnerabilities in the July 2026 advisory, spanning SharePoint, Dynamics, Copilot, and Entra. Here are a few notable vulnerabilities from the advisory which AppTrana covers.

CVE Product CVSS Description
CVE-2026-50522 SharePoint Server 9.8 Deserialization vulnerability lets an authenticated Site Owner achieve RCE via crafted serialized .NET objects
CVE-2026-58644 SharePoint Server 9.8 Same deserialization RCE class as CVE-2026-50522, exploitable via crafted serialized payloads
CVE-2026-55040 SharePoint Server 9.1 Weak authentication vulnerability allows an anonymous connection to bypass access controls
CVE-2026-55944 Dynamics NAV / Business Central 9.8 Unauthenticated RCE via a crafted login request exploiting deserialization on the exposed web service
CVE-2026-48561 Microsoft Copilot (Android / Edge) 9.6 Command injection via the Copilot web/API interface; AppTrana’s OS command injection rules (shell metacharacter pattern detection) apply directly to this attack surface
CVE-2026-41106 Microsoft 365 Copilot 9.3 Open redirect vulnerability sends users from the Copilot web surface to an untrusted site; covered under AppTrana’s redirect-injection rules (Microsoft has also cloud-mitigated this; no customer action required)
CVE-2026-57100 Microsoft Entra Provisioning Service 9.9 SSRF vulnerability allows privilege escalation via the provisioning service; covered under AppTrana’s generic SSRF detection rules (Microsoft has fixed this server-side; verify on-prem Entra Connect exposure separately)
Bhargavi Pallati

Bhargavi Pallati is a Security Researcher at Indusface with experience in threat analysis, web application security, and detection engineering. She has a strong background as a Security Analyst and has worked extensively on vulnerability assessment and coverage verification. Bhargavi focuses on analyzing emerging attack patterns, strengthening application-level defenses, and improving security controls through continuous research and learning.