CVE-2024-29059: Microsoft .NET Framework Information Disclosure Vulnerability

CVE-2024-29059 is an information disclosure vulnerability in Microsoft .NET Framework. It can expose an ObjRef URI to an attacker, which CISA notes may ultimately enable remote code execution. For IT and security teams, this matters because .NET Framework is widely deployed on Windows servers and workstations that host business applications, web services, and internal tools; successful abuse could give an attacker a foothold for further compromise. Confirm all version, configuration, and patch details against the official Microsoft advisory before acting.

How it works

The weakness is classified as CWE-209, which covers information exposure that can leak sensitive details an attacker should not see. In this case, the vulnerability allows disclosure of an ObjRef URI. An ObjRef is a .NET remoting construct that identifies a remote object; once an attacker obtains that URI, they may be able to interact with the object in ways that escalate to remote code execution. Exact exploitation steps, required privileges, or network conditions are not provided in the public summary, so treat the issue as an information-leak primitive that can chain into code execution and verify the precise attack surface against the vendor advisory. No public details indicate that ransomware groups have used this CVE.

Am I affected? How to find it in your systems

Microsoft .NET Framework is commonly installed on Windows Server and client systems that run ASP.NET applications, desktop software, services, or remoting endpoints. Inventory every Windows host for the presence of .NET Framework runtimes and any applications that rely on .NET remoting or related serialization features.

• Use software inventory tools, PowerShell queries against installed products, or configuration-management databases to list .NET Framework versions and the applications that depend on them.
• Review application configuration for remoting, ObjRef usage, or endpoints that accept untrusted input that could trigger the disclosure.
• Check Microsoft’s security update catalog and the specific advisory for CVE-2024-29059 to determine which builds are listed as vulnerable; do not assume version ranges without confirmation.
• For detection of possible exploitation, monitor application and system logs for unexpected remoting activity, anomalous object-reference traffic, or error messages that may leak internal URIs. Correlate with network telemetry for unusual inbound connections to .NET services. Because public indicators of compromise are limited, treat any unexplained remoting anomalies as high priority for investigation.

How to remediate

The primary remediation is to apply the vendor-supplied update for Microsoft .NET Framework that addresses CVE-2024-29059. Follow Microsoft’s published instructions exactly; CISA’s required action is to apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

• Deploy the security update through your normal patch-management process (WSUS, SCCM/MECM, Intune, or manual installation) and verify successful installation on all affected hosts.
• After patching, restart services or systems as required by the advisory and re-test critical applications that use .NET remoting.
• As a general hardening step for this class of issue, reduce the attack surface by disabling unused remoting features, restricting which processes can create or resolve ObjRefs, and ensuring applications do not expose detailed error information to untrusted callers.

If you can't patch immediately

Until the update can be applied, reduce exposure with compensating controls that limit an attacker’s ability to reach the vulnerable component or to use a leaked ObjRef.

• Segment systems that host .NET Framework applications so that only authorized management and application networks can reach remoting ports or endpoints.
• Apply network-level filtering or virtual patching (for example, WAF or IPS rules that block suspicious remoting patterns) if your security tools support signatures or custom rules for .NET remoting traffic; confirm rule efficacy against the vendor advisory.
• Disable or restrict the affected remoting functionality where business requirements allow; if the feature is not required, turn it off.
• Increase monitoring and alerting on the hosts and network paths that remain exposed, focusing on anomalous object-reference activity and unexpected process creation that could indicate follow-on code execution.

If your data may have been exposed

Actively exploited vulnerabilities of this type can lead to broader compromise and data exposure. If you have reason to believe systems were targeted before patching, treat the incident as a potential breach: isolate affected hosts, preserve logs, and begin forensic review. As a quick personal check, you can run a free exposure scan of your email address against known breach data to see whether credentials or other information have already appeared in public dumps.