CVE-2026-107820 x64dbg-MCP Server vulnerable to pre-authentication denial of service through Content-Length integer overflow
Unauthenticated attackers can crash the x64dbg debugger by sending a large Content-Length header, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-107820?
CVE-2026-107820 is a medium-severity vulnerability in duty1g x64dbg-mcp-server, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
x64dbg-MCP Server is a native Model Context Protocol (MCP) plugin for x64dbg that exposes the debugger's full functionality over HTTP. Prior to 1.2, src/core/mcp_server.zig parses an unbounded Content-Length value in parseContentLength() and uses it in unchecked usize addition in wsRecv() before token authentication. The server listens on 0.0.0.0 by default in affected versions. An unauthenticated network client can supply a near-maximum Content-Length value to trigger a runtime integer-overflow panic in Debug and ReleaseSafe builds, terminating the entire x64dbg process and its live debugging session. The overflowed value is used only in a comparison, so the impact is limited to denial of service rather than memory corruption or code execution. This issue is fixed in version 1.2.
Weakness: CWE-190
Which versions are affected by CVE-2026-107820?
How do I fix CVE-2026-107820?
No fix has been published for CVE-2026-107820 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-107820 being exploited?
There is no known exploitation of CVE-2026-107820 in the wild and no public exploit code.