CVE-2026-111767
Description
A flaw was found in the Model Context Protocol (MCP) TypeScript SDK (@modelcontextprotocol/sdk). The experimental task storage feature (taskStore) does not verify which client session created a given task when multiple clients share a task store. A remote attacker sharing the same server instance can exploit this flaw to list, read, and cancel tasks created by other sessions. This results in unauthorized information disclosure and disruption of task processing.
Statement
Red Hat Product Security has rated this flaw as having an Important severity because missing session boundaries within the shared task storage mechanism allow concurrent connections to inspect, enumerate, or abort tasks belonging to other clients. This classification reflects the high risk of cross-session data disclosure and execution tampering over the network without requiring administrative privileges, exceeding the lower Moderate threshold despite being confined to servers that explicitly enable the optional task store. In Red Hat environments delivering this component, exposure is limited to deployments where multi-session server instances actively utilize the experimental in-memory task tracking feature.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.3 | N/A | 8.6 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | High |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Access control checks for specific user data or functionality can be bypassed.
Access Control
Technical Impact: Gain Privileges or Assume Identity
Horizontal escalation of privilege is possible (one user can view/modify information of another user).
Access Control
Technical Impact: Gain Privileges or Assume Identity
Vertical escalation of privilege is possible if the user-controlled key is actually a flag that indicates administrator status, allowing the attacker to gain administrative access.
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