{"data":{"id":"453d7cc8-0735-4752-8c4e-c6792e82d381","title":"GHSA-hvrp-rf83-w775: MCP Python SDK: Experimental task handlers allow any client to access and cancel other clients' tasks","summary":"The MCP Python SDK's experimental task handlers, enabled through `server.experimental.enable_tasks()`, did not check which session created a task before acting on it. On a multi-client server, any connected client could list, read, cancel, and consume queued messages such as elicitation requests belonging to other clients' tasks.","solution":"Upgrade to version 1.27.2 or later, in which task IDs generated by `run_task()` embed an opaque per-session marker and the default handlers restrict each session to its own tasks. Alternatively, leave the experimental tasks feature disabled, or register task handlers that validate session ownership.","labels":["security"],"sourceUrl":"https://github.com/advisories/GHSA-hvrp-rf83-w775","publishedAt":"2026-07-16T19:56:12.000Z","cveId":"CVE-2026-52870","cweIds":["CWE-862"],"cvssScore":"7.6","cvssSeverity":"high","severity":"high","attackType":["other"],"issueType":"vulnerability","affectedPackages":["mcp@>= 1.23.0, <= 1.27.1 (fixed: 1.27.2)"],"affectedPackageNames":["mcp"],"affectedVendors":[],"affectedVendorsRaw":["MCP Python SDK"],"classifierModel":"claude-haiku-5-5","classifierPromptVersion":"v4","summaryPromptVersion":"v2","headline":null,"headlinePromptVersion":null,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L","attackVector":"network","attackComplexity":"low","privilegesRequired":"low","userInteraction":"none","exploitMaturity":"unknown","epssScore":0.00388,"epssCheckedAt":"2026-10-10T04:57:25.496Z","kevDateAdded":null,"advisoryAliases":["GHSA-hvrp-rf83-w775"],"affectedPackagesSource":null,"affectedPackagesCheckedAt":null,"patchAvailable":true,"disclosureDate":"2026-07-16T19:56:12.000Z","capecIds":["CAPEC-122"],"crossRefCount":0,"attackSophistication":"trivial","impactType":["confidentiality","integrity","availability"],"aiComponentTargeted":"framework","llmSpecific":false,"classifierConfidence":0.9,"researchCategory":null,"atlasIds":null}}