CVE-2017-0247
HIGHCVE-2017-0247 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in microsoft asp.net model view controller. 1 public exploit reference exists, so weaponization risk is real. O3 Security detects and blocks CVE-2017-0247 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
A denial of service vulnerability exists when the ASP.NET Core fails to properly validate web requests. NOTE: Microsoft has not commented on third-party claims that the issue is that…
Description
A denial of service vulnerability exists when the ASP.NET Core fails to properly validate web requests. NOTE: Microsoft has not commented on third-party claims that the issue is that the TextEncoder.EncodeCore function in the System.Text.Encodings.Web package in ASP.NET Core Mvc before 1.0.4 and 1.1.x before 1.1.3 allows remote attackers to cause a denial of service by leveraging failure to properly calculate the length of 4-byte characters in the Unicode Non-Character range.
Affected Products
asp.net model view controllermicrosoftmicrosoft.aspnetcore.mvc.abstractionsmicrosoftmicrosoft.aspnetcore.mvc.apiexplorermicrosoftmicrosoft.aspnetcore.mvc.corsmicrosoftmicrosoft.aspnetcore.mvc.dataannotationsmicrosoftmicrosoft.aspnetcore.mvc.formatters.jsonmicrosoftResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every microsoft asp.net model view controller deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2017-0247 yet — track the microsoft asp.net model view controller advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2017-0247 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2017-0247. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2017-0247 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2017-0247 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.