CVE Alert: CVE-2025-55240 – Microsoft – Microsoft Visual Studio 2017 version 15.9 (includes 15.0 – 15.8)

Risk verdict

High risk of local privilege escalation if an authenticated user interacts with Visual Studio; no explicit KEV or SSVC exploitation state reported.

Why this matters

An attacker with a normal user account could leverage Visual Studio workflows or extensions to gain higher rights on the host, potentially accessing source code, project files, and build tooling. In enterprises, this raises the risk of broader compromise in developer estates and CI/CD environments, especially where dev workstations have broad access to network resources.

Most likely attack path

Attacker already has local access and a low-privilege user account. They craft or coerce the user to run or load a malicious extension/workflow within Visual Studio, taking advantage of the elevated context to perform privileged actions. Exploitation requires user interaction, so it hinges on a deceptive or bundled component being executed locally, limiting remote spread but enabling rapid post-exploitation on the host.

Who is most exposed

Dev workstations and developer laptops with Visual Studio installed are most at risk, particularly in organisations where developers routinely install extensions or run custom build tasks with elevated rights.

Detection ideas

• Unusual Visual Studio process activity (devenv.exe) performing privileged actions after user interaction.
• New or modified processes/extensions invoked by Visual Studio attempting elevated operations.
• Unexpected token/permissions changes or ACL edits tied to Visual Studio-related files or directories.
• Anomalous build or extension activity outside normal development workflows.
• Elevated creator/process lineage during code build or deployment steps.

Mitigation and prioritisation

• Apply the latest non-affected Visual Studio builds for all tracked channels (address the specific version ranges listed as affected).
• Enforce least-privilege: limit Visual Studio and extensions to standard user contexts; restrict elevated actions.
• Tighten application control: sign and whitelisting for extensions; disable or sandbox untrusted extensions.
• Network/workspace hygiene: segment dev machines; restrict access to sensitive repos from untrusted hosts.
• Change-management: deploy patches in a staged manner; verify build pipelines remain secure post-upgrade.