CVE-2025-2749

What it actually does

CVE-2025-2749 is an authenticated remote code execution vulnerability in Kentico Xperience through version 13.0.178. A highly privileged authenticated user with access to the Staging Sync Server functionality can abuse improper path handling to traverse directories and upload arbitrary files to attacker-controlled relative paths. If the uploaded content is placed in a server-executable location, such as an ASP.NET-accessible web path, the attacker can execute code on the application server with the privileges of the Kentico/IIS application pool. Successful exploitation can provide full confidentiality, integrity, and availability impact on the affected application and potentially the underlying host.

Why it matters to the business

An attacker who already has privileged Kentico access can turn that access into control of the web server, enabling data theft, website defacement, malware deployment, lateral movement, or disruption of content-management operations. Because this vulnerability is listed in CISA KEV, has active in-the-wild exploitation, and has a remediation deadline of 2026-05-04, organizations running exposed or internet-facing Kentico Xperience instances should treat it as a high-priority operational risk despite the requirement for prior authentication.

How an attack unfolds

An attacker first obtains valid Kentico credentials with sufficient privileges to use or reach the Staging Sync Server feature. This access may come from credential theft, phishing, password reuse, compromised administrator accounts, or abuse of an existing integration account. The attacker then sends crafted staging synchronization requests containing file-upload data and path traversal sequences so that the server writes attacker-controlled content outside the intended staging location. By choosing a path that is processed by ASP.NET, the attacker can upload a script or web shell and then request it over HTTP to execute commands on the server. From there, the attacker may enumerate configuration files, extract secrets, access databases using application credentials, modify site content, deploy persistence, or pivot further into the environment. Public reporting indicates active exploitation in the wild, so defenders should assume exposed vulnerable systems may have been probed or abused.

How to fix it

Upgrade Kentico Xperience to a vendor-fixed release newer than 13.0.178 as soon as an applicable patched version is available from Kentico, and verify that all production, staging, disaster recovery, and legacy instances are included. If immediate upgrade is not possible, restrict Staging Sync Server access to trusted administrative networks only, disable staging synchronization where it is not required, enforce strong authentication and least privilege for Kentico administrative and integration accounts, and block traversal patterns and unexpected file-upload requests at the web application firewall where feasible. Review file-system permissions so the application pool cannot write to executable web directories unless strictly required. Remove any unauthorized uploaded executable files and rotate secrets if compromise is suspected.

How to confirm the fix worked

Confirm the deployed Kentico Xperience version is greater than 13.0.178 or matches the vendor-advised fixed build. Verify that Staging Sync Server endpoints are not internet-accessible unless explicitly required and protected by strict access controls. Test that authenticated staging upload workflows cannot write files outside intended directories using path traversal sequences such as ../ or ..\. Inspect the webroot and Kentico application directories for recently created or modified executable files, especially .aspx, .ashx, .asmx, .config, .dll, or script files. Validate that IIS/application logs show no successful requests to unexpected newly uploaded files. Confirm that file-system ACLs prevent the web application identity from writing to server-executable directories where possible.

Typical attack path

1. Identify a Kentico Xperience instance and confirm the presence of Staging Sync Server functionality.
2. Obtain or reuse authenticated credentials with sufficient privilege to invoke staging synchronization operations.
3. Submit a crafted staging sync request that includes path traversal sequences in the file destination or related upload metadata.
4. Write an attacker-controlled file, such as an ASP.NET script or web shell, into a server-executable web-accessible directory.
5. Access the uploaded file over HTTP to execute server-side code under the web application’s identity.
6. Use the resulting code execution to read configuration files, extract secrets, alter content, deploy persistence, or move laterally.

How to detect it

Review IIS access logs, Kentico application/event logs, reverse proxy logs, WAF logs, EDR telemetry, and file-integrity monitoring for evidence of exploitation. Focus on authenticated POST requests to Kentico staging synchronization endpoints, especially requests containing path traversal sequences, unusual file names, encoded traversal characters, or attempts to write ASP.NET-executable files. Look for newly created or modified .aspx, .ashx, .asmx, .config, .dll, or script files in web-accessible Kentico directories after suspicious staging activity. Correlate suspicious uploads with subsequent GET requests to the uploaded file and with abnormal process execution by IIS worker processes, such as command shells, PowerShell, scripting engines, archive utilities, or network tools. Because exploitation requires authentication, investigate Kentico administrative logins from unfamiliar IP addresses, impossible travel patterns, new or modified users, unexpected staging configuration changes, and activity by service or integration accounts outside normal maintenance windows. If web shells are found, search for outbound connections, credential access, database dumping, archive creation, and persistence artifacts.

• /CMSPages/Staging/SyncServer.asmx
• POST /CMSPages/Staging/SyncServer.asmx
• SyncServer.asmx
• Staging Sync Server
• ../
• ..\\
• %2e%2e%2f
• %2e%2e%5c
• .aspx
• .ashx
• .asmx
• <%@ Page Language=
• <%@ WebHandler Language=
• System.Diagnostics.Process
• cmd.exe
• powershell.exe
• w3wp.exe -> cmd.exe
• w3wp.exe -> powershell.exe
• w3wp.exe -> cscript.exe
• w3wp.exe -> wscript.exe

What your security team should do

• Inventory all Kentico Xperience deployments, including non-production, staging, legacy, and externally hosted instances, and identify versions through 13.0.178.
• Prioritize remediation because the vulnerability is in CISA KEV, is reported as actively exploited in the wild, and has a CISA due date of 2026-05-04.
• Upgrade to a vendor-fixed Kentico Xperience release or apply vendor-provided hotfix guidance as soon as available.
• Temporarily restrict or disable Staging Sync Server functionality if it is not required, especially on internet-facing systems.
• Review Kentico administrator, staging, and integration accounts for excessive privileges, stale credentials, weak passwords, or suspicious recent activity.
• Hunt for signs of arbitrary file upload, path traversal, web shell placement, and suspicious child processes spawned by the web application worker process.
• Place compensating controls at the edge, including WAF rules for path traversal and unexpected uploads to staging synchronization endpoints.
• If exploitation is suspected, isolate the host, preserve IIS/Kentico/application logs, collect recent file-system changes, rotate application/database secrets, and perform full incident response.