Permissive Cross-domain Policy with Untrusted Domains Affecting io.modelcontextprotocol.sdk:mcp-core package, versions [,1.0.1)[1.1.0,1.1.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published31 Mar 2026
- disclosed30 Mar 2026
- creditSrikanth Ramu
Introduced: 30 Mar 2026
CVE-2026-34237 (opens in a new tab)How to fix?
Upgrade io.modelcontextprotocol.sdk:mcp-core to version 1.0.1, 1.1.1 or higher.
Overview
Affected versions of this package are vulnerable to Permissive Cross-domain Policy with Untrusted Domains via the HttpServletSseServerTransportProvider and HttpServletStreamableServerTransportProvider classes. An attacker can access sensitive session information by leveraging a malicious web page to trigger cross-origin requests, allowing unauthorized reading of server-sent events and subsequent relay of requests using the victim's browser.