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CVE-2026-42559

RMCP is an official Rust SDK for the Model Context Protocol. Prior to version 1.4.0, the rmcp crate's Streamable HTTP server transport (crates/rmcp/src/transport/streamable_http_server/) did not validate the incoming Host header. This allowed a malicious public website, via a DNS rebinding attack, to send authenticated requests to an MCP server running on the victim's loopback or private-network interface. This vulnerability is fixed in 1.4.0.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:74810e08f2912526f7f189fe47372225f5e0956270ef1f6ba711a2b59eb96790
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-346","description":"CWE-346: Origin Validation Error","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-350","description":"CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/problemTypes/1/descriptions/0

Affected products and versions

1 source assertion
{"product":"rust-sdk","vendor":"modelcontextprotocol","versions":[{"status":"affected","version":"< 1.4.0"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":8.8,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-346","description":"CWE-346: Origin Validation Error","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-350","description":"CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/problemTypes/1/descriptions/0

Source references

5 source assertions
{"name":"https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/references/4
{"name":"https://github.com/modelcontextprotocol/rust-sdk/issues/815","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/rust-sdk/issues/815"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/references/1
{"name":"https://github.com/modelcontextprotocol/rust-sdk/issues/822","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/rust-sdk/issues/822"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/references/2
{"name":"https://github.com/modelcontextprotocol/rust-sdk/pull/764","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/rust-sdk/pull/764"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/references/3
{"name":"https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx","tags":["x_refsource_CONFIRM"],"url":"https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:031f352e381fc9f9eb66fcea85bbfb88725d848e4afb2653cd195abdc8da1754 · sha256:22ea3b86a319f998… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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