Improper Certificate Validation in Microsoft Visual Studio Enables Network Spoofing

Improper certificate validation in Visual Studio allows an unauthorized attacker to perform spoofing over a network.

• Microsoft Visual Studio 2017 version 15.9: affected starting at 15.9.0 and including versions less than 15.9.84.
• Microsoft Visual Studio 2019 version 16.11: affected starting at 16.11.0 and including versions less than 16.11.62.
• Microsoft Visual Studio 2022 version 17.14: affected starting at 17.14.0 and including versions less than 17.14.44.
• Microsoft Visual Studio 2026 version 18.11: affected starting at 18.11.0 and including versions less than 18.11.3.

The record does not establish the status of Visual Studio branches outside these four listed branches.

Microsoft Visual Studio contains improper certificate validation, so a certificate or network identity may not be evaluated against the intended trust rules. The record states that an unauthorized attacker can reach the vulnerable behavior over a network and perform spoofing without prior privileges or user interaction, although exploitation requires high complexity. Successful exploitation could cause Visual Studio to accept a spoofed identity or network data, which is an inference consistent with the recorded confidentiality and integrity impact. The record does not identify the affected Visual Studio subsystem, protocol, certificate property, or specific processing path.

The vulnerability is network reachable. The record characterizes exploitation as requiring no authentication or privileges and no user interaction, while also requiring high attack complexity. The record does not confirm exploitation in the wild and does not provide a public exploit reference; the exploitation and public exploit status fields contain no confirmed data. This lack of information should not be interpreted as evidence that exploitation is absent.

Successful exploitation could allow spoofing of an identity or data in network interactions handled by Visual Studio. The record characterizes the potential impact as high for confidentiality and integrity, while no availability impact is identified. Real-world consequences could include development tooling or users making decisions based on spoofed network information, but the record does not identify a particular workflow, data set, or system. The stated scope is unchanged, so the recorded impact remains within the affected system.

Development and build teams using affected Microsoft Visual Studio branches may face spoofing risk in network interactions performed by the development tool. If exploited, an attacker could cause the software or an operator to trust an invalid network identity, potentially exposing or altering exchanged data. The record does not identify the specific workflows, data types, or dependent systems that would be affected. Because the described attack is network reachable and requires no privileges, inventory and patching of development systems should be prioritized.

1. Update Microsoft Visual Studio using Microsoft's security update so that each branch is moved out of the affected range. The boundaries to verify are 15.9.84 for Visual Studio 2017 version 15.9, 16.11.62 for Visual Studio 2019 version 16.11, 17.14.44 for Visual Studio 2022 version 17.14, and 18.11.3 for Visual Studio 2026 version 18.11.
2. After updating, verify the actual product branch and installed version on every workstation, build server, and automation system.
3. Do not combine release branches when assessing remediation status. An update boundary for one branch does not establish the status of another branch.
4. The record does not provide a vendor-specific interim mitigation. If updating is not immediately possible, track the system as remaining within the affected range and apply internal risk controls, rather than treating generic network controls as a confirmed fix.

1. Inventory all Microsoft Visual Studio installations on developer workstations, build servers, and development automation systems.
2. Record the exact product branch and installed version for each system, then compare them with the affected and fixed boundaries listed in affected_summary and remediation.
3. Identify systems that have not been updated according to the corresponding Microsoft security update, prioritizing systems that perform network connections across less-trusted environments.
4. As a precaution, review network telemetry for unusual certificate identity changes or certificate validation failures associated with Visual Studio. The record provides no specific IOC, log event, endpoint, or protocol, so the absence of such evidence does not prove that a system is safe.