CVE-2026-59951 concerns lifecycle retention of stateful MCP sessions after termination and rejection. Newer versions introduce default timeouts and count bounds, which remain configurable and therefore require deployment checks. It is not the same bug as per-request memory amplification. A modest per-request size cap cannot solve an unlimited number of…
Inspect the ClaimsCase · DiggingBeagle record
Python MCP SDK retained terminated sessions and initialization state
Independent from request-body buffering, stale Streamable HTTP session entries could accumulate indefinitely.
Scope
Research claim attributed to the cited report, with limitations from intake DB-RADAR-CP7-CP7A-057.
Assessment profile
Assessment method- Setting
- research demonstration
- Exploitation
- demonstrated
- Evidence
- Grade C
- Remediation
- fixed reported
- AI role
- AGAINST AI
Basis and provenance
The advisory concerns state retained after session termination rather than individual oversize requests. Bounds on lifetime and count were reported, subject to deployment configuration. Assessment uses the pinned Claims and source identities; public primary pages were not independently retrievable during this run. Impact remains unrated because field consequence or a comparable scoring rubric is not established.
Assessed Oct 15, 2026 using diggingbeagle.assessment/1.
Evidence basis: CLM-CP7A-MCP-SESSION-LEAK · Python MCP SDK session leakage despite DELETE corrected in CVE-2026-59951 — original research or disclosure
At a glance
Independent reproduction or full primary-document access in this research run was not achieved. Real-world incidence and broader model or deployment generalization are not established unless specifically stated.
Limits and uncertaintyFull account
CVE-2026-59951 concerns lifecycle retention of stateful MCP sessions after termination and rejection. Newer versions introduce default timeouts and count bounds, which remain configurable and therefore require deployment checks. It is not the same bug as per-request memory amplification.
A modest per-request size cap cannot solve an unlimited number of abandoned session objects. Session expiry, delete handling and capacity limits have to hold across rejection, reconnect and failure paths.
Claims & evidence
CLM-CP7A-MCP-SESSION-LEAKThe cited authors or maintainers report the following bounded finding: Independent from request-body buffering, stale Streamable HTTP session entries could accumulate indefinitely.supported
Basis: reported finding
- supportsPython MCP SDK session leakage despite DELETE corrected in CVE-2026-59951 — original research or disclosureprimary disclosure
Original primary document, reported finding and evaluation context; checkpoint DB-RADAR-CP7-CP7A-057
Unknowns and contradictions
- Independent reproduction or full primary-document access in this research run was not achieved.
- Real-world incidence and broader model or deployment generalization are not established unless specifically stated.
Sources and citation
Material revision history
- Oct 15, 2026 · Canonical change recorded · new in release · revision 150