CVE-2026-34742High· 8.0▾ TwilightA flaw was found in the Model Context Protocol (MCP) Go SDK. When an HTTP-based MCP server is run on localhost without authentication, a malicious website can exploit a DNS rebinding vulnerability. This allows the attacker to bypass same-o…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 44 · likelihood 0.1 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Exploit-prediction probability, daily snapshots since Aug 2.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CSAF
0.5%
0.5% → 0.7%
Last analysed / modified upstream
8.1 → 8
A flaw was found in the Model Context Protocol (MCP) Go SDK. When an HTTP-based MCP server is run on localhost without authentication, a malicious website can exploit a DNS rebinding vulnerability. This allows the attacker to bypass same-origin policy restrictions and send requests to the local MCP server. Consequently, an attacker could invoke tools or access resources exposed by the MCP server on behalf of the user.
github.com/modelcontextprotocol/go-sdk: Model Context Protocol (MCP) Go SDK: DNS rebinding vulnerability allows unauthorized access — rated Important by Red Hat. Released 2026-04-02, updated 2026-10-15.
Affected:
Fixed:
No fix planned:
Not affected:
Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258 https://access.redhat.com/errata/RHSA-2026:21772
Workarounds / mitigations:
Affected packages:
github.com/modelcontextprotocol/go-sdk < 1.4.0Patched in:
github.com/modelcontextprotocol/go-sdk 1.4.0Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2025-66416High· 8.1mcp: DNS Rebinding Protection Disabled by Default in Model Context Protocol Python SDK (CVE-2025-66416)
CVE-2026-27896High· 7.2modelcontextprotocol/go-sdk: improper handling of case sensitivity (CVE-2026-27896)
CVE-2026-115877Medium· 5.4twisted: Twisted: HTTP request smuggling via improper header delimiter handling (CVE-2026-115877)
CVE-2026-114140High· 7.8nbconvert: nbconvert: arbitrary file write via path traversal in ExtractOutputPreprocessor (CVE-2026-114140)
CVE-2026-114145High· 7.5GitPython: GitPython: arbitrary code execution via improper submodule path validation (CVE-2026-114145)
CVE-2026-114136High· 7.5djangorestframework: djangorestframework: Denial of Service via improper charset handling in JSON parser (CVE-2026-114136)