@modelcontextprotocol/sdk has cross-client data leak via shared server/transport instance reuse

Summary

CVE	CVE-2026-25536
State	PUBLISHED
Assigner	GitHub_M
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-02-04 22:15:59 UTC
Updated	2026-07-15 02:18:54 UTC
Description	MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. From version 1.10.0 to 1.25.3, cross-client response data leak when a single McpServer/Server and transport instance is reused across multiple client connections, most commonly in stateless StreamableHTTPServerTransport deployments. This issue has been patched in version 1.26.0.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

EPSS: 0.002670000 probability, percentile 0.184390000 (date 2026-07-15)

Problem Types: CWE-362 | CWE-367 | CWE-362 CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') | CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

Version	Source	Type	Score	Severity	Vector
3.1	ADP	CVSS	7.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N`
3.1	[email protected]	Secondary	7.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N`
3.1	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	Secondary	7.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N`
3.1	CNA	DECLARED	7.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N`

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

NVD Known Affected Configurations (CPE 2.3)

Type	Vendor	Product	Version	Update	Edition	Language
Application	Lfprojects	Mcp Typescript Sdk	All	All	All	All

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Modelcontextprotocol	Typescript-sdk	affected >= 1.10.0, < 1.26.0	Not specified
ADP	Red Hat	Red Hat Ansible Automation Platform 2.6	unaffected 1772196222 * rpm	Not specified

References

Reference	Source	Link	Tags
access.redhat.com/errata/RHSA-2026:3960	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	access.redhat.com
github.com/modelcontextprotocol/typescript-sdk/issues/243	[email protected]	github.com	Issue Tracking, Vendor Advisory
github.com/modelcontextprotocol/typescript-sdk/issues/204	[email protected]	github.com	Issue Tracking, Vendor Advisory
access.redhat.com/security/cve/CVE-2026-25536	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	access.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25536.json	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	security.access.redhat.com
github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-...	[email protected]	github.com	Mitigation, Vendor Advisory
bugzilla.redhat.com/show_bug.cgi	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	bugzilla.redhat.com
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

Additional Advisory Data

Source	Time	Event
ADP	2026-02-04T22:00:54.864Z	Reported to Red Hat.
ADP	2026-02-04T21:29:38.276Z	Made public.

Solutions

ADP: RHSA-2026:3960: Red Hat Ansible Automation Platform 2.6

Workarounds

ADP: 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.

There are currently no legacy QID mappings associated with this CVE.