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CVE-2026-67432

MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:681bd5e89f5abf10c9166be92e58629185c01897f15a846c8127dfe41eece833
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0

Affected products and versions

1 source assertion
{"product":"ruby-sdk","vendor":"modelcontextprotocol","versions":[{"status":"affected","version":"< 0.23.0"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

1 source assertion
{"cweId":"CWE-770","description":"CWE-770: Allocation of Resources Without Limits or Throttling","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /containers/cna/problemTypes/0/descriptions/0

Source references

4 source assertions
{"name":"https://github.com/modelcontextprotocol/ruby-sdk/commit/772e0cb1f9db69312006926eee59a7287ad50166","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/commit/772e0cb1f9db69312006926eee59a7287ad50166"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /containers/cna/references/1
{"name":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0","tags":["x_refsource_MISC"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /containers/cna/references/2
{"tags":["exploit"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-h669-8m4g-r2hc"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /containers/adp/0/references/0
{"name":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-h669-8m4g-r2hc","tags":["x_refsource_CONFIRM"],"url":"https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-h669-8m4g-r2hc"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:1f0cd70a814127e07a13b7ea9216ea7d3d2786b53058b571ff67e7d36f5f6e2e · sha256:121a2e715f7a508b… · /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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