{"items":[{"id":"NVI-00015365","kind":"vulnerability","title":"MCP Ruby SDK: Ruby SSE Session Poisoning","revision":2,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected.","NVD lastModified does not establish freshness of every associated CPE record."],"lifecycle":"active","identifiers":["GHSA-5p9g-j988-pcwv","CVE-2026-67431"],"plain_summary":"GitHub lists this reviewed advisory for mcp. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-3fcac0431a32d996622e0d1194fecb70"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-10-24T13:10:00.147Z","value":"8.3 HIGH (4.0)","meaning":"security-advisories@github.com severity; no combined Null risk score.","source_id":"sr-3fcac0431a32d996622e0d1194fecb70"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-60567520a4d3562c986a6a4d2ef2e351","url":"https://github.com/advisories/GHSA-5p9g-j988-pcwv","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-5p9g-j988-pcwv","publisher":"GitHub Advisory Database","observed_at":"2026-11-03T09:58:49.818Z"},{"id":"sr-3fcac0431a32d996622e0d1194fecb70","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-67431","basis":"official_catalog","notes":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","title":"CVE-2026-67431","publisher":"NIST National Vulnerability Database","observed_at":"2026-11-08T15:07:43.109Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-60567520a4d3562c986a6a4d2ef2e351"],"technology":"mcp","known_exclusions":[],"conditions_summary":"### Summary\n**Vulnerability**: Missing Session Ownership Validation in the Ruby MCP SDK's Streamable and SSE HTTP transport implementation. Any attacker with a stolen session ID can execute tools with the victim's session. This is a silent attack - the victim's session is compromised and being used for unauthorized actions, but it is hard to know for the victim\n\n### Details\nhttps://github.com/modelcontextprotocol/ruby-sdk/blob/main/lib/mcp/server/transports/streamable_http_transport.rb#L260-L278\n\n**Victim** starts a legitimate MCP session and receives session ID abc-123\n**Attacker** obtains the session ID (various means - network sniffing, logs, etc. out of scope for this analysis)\n**Attacker** sends POST to /messages/abc-123 with a tool call\n**Server** accepts the request (no ownership validation!)\n**Server** executes the tool and sends response to victim's SSE stream\n**Victim** receives attacker's response, thinking it's legitimate\n\n### PoC\nattacker_client.py\nlegitimate_client.py\n\n**Prerequisites**\n\n1. Python 3.8+\n2. Install dependenc","public_affected_ranges":["<= 0.22.0"]}],"null_published_at":"2026-11-08T19:53:44.051Z","source_updated_at":"2026-07-30T14:44:29.000Z","source_disclosed_at":"2026-07-30T14:44:28.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"Source facts changed; compare the preserved prior revision.","null_first_observed_at":"2026-11-03T09:58:49.818Z"},{"id":"NVI-00015365","kind":"vulnerability","title":"MCP Ruby SDK: Ruby SSE Session Poisoning","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-5p9g-j988-pcwv","CVE-2026-67431"],"plain_summary":"GitHub lists this reviewed advisory for mcp. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-60567520a4d3562c986a6a4d2ef2e351"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-60567520a4d3562c986a6a4d2ef2e351","url":"https://github.com/advisories/GHSA-5p9g-j988-pcwv","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-5p9g-j988-pcwv","publisher":"GitHub Advisory Database","observed_at":"2026-11-03T09:58:49.818Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-60567520a4d3562c986a6a4d2ef2e351"],"technology":"mcp","known_exclusions":[],"conditions_summary":"### Summary\n**Vulnerability**: Missing Session Ownership Validation in the Ruby MCP SDK's Streamable and SSE HTTP transport implementation. Any attacker with a stolen session ID can execute tools with the victim's session. This is a silent attack - the victim's session is compromised and being used for unauthorized actions, but it is hard to know for the victim\n\n### Details\nhttps://github.com/modelcontextprotocol/ruby-sdk/blob/main/lib/mcp/server/transports/streamable_http_transport.rb#L260-L278\n\n**Victim** starts a legitimate MCP session and receives session ID abc-123\n**Attacker** obtains the session ID (various means - network sniffing, logs, etc. out of scope for this analysis)\n**Attacker** sends POST to /messages/abc-123 with a tool call\n**Server** accepts the request (no ownership validation!)\n**Server** executes the tool and sends response to victim's SSE stream\n**Victim** receives attacker's response, thinking it's legitimate\n\n### PoC\nattacker_client.py\nlegitimate_client.py\n\n**Prerequisites**\n\n1. Python 3.8+\n2. Install dependenc","public_affected_ranges":["<= 0.22.0"]}],"null_published_at":"2026-11-03T10:03:31.358Z","source_updated_at":"2026-07-30T14:44:29.000Z","source_disclosed_at":"2026-07-30T14:44:28.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-03T09:58:49.818Z"}],"next_cursor":null,"snapshot_revision":"42594"}