What is the CVSS score of CVE-2026-25536?

CVE-2026-25536 has a CVSS 3.1 base score of 7.1 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N. EPSS exploitation probability: 0.0%.

Is there a public PoC exploit available for CVE-2026-25536?

Yes, a public proof-of-concept exploit is available for CVE-2026-25536. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-25536?

Within 24 hours: Identify all systems and applications using MCP TypeScript SDK and document affected inventory. Within 7 days: Implement network segmentation to restrict MCP component communication and increase monitoring for suspicious activity. Within 30 days: Monitor vendor advisories for patch release and establish testing environment to validate patch deployment once available.

Mcp Typescript Sdk CVE-2026-25536

HIGH

Race Condition (CWE-362)

2026-02-04 security-advisories@github.com

GHSA-345p-7cg4-v4c7

Information Disclosure Race Condition Mcp Typescript Sdk Lfprojects

7.1

CVSS 3.1 · Vendor: github

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Establish authenticated connection to MCP server
Exploit

Reuse McpServer instance across multiple clients
Execution

Intercept response data from other clients
Impact

Extract sensitive information from cross-client leak

Vulnerability Assessment

Weakness	CWE CWE-362 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V15 - Secure Coding and Architecture Concurrency control, locking MITRE ATT&CK 1 technique across 1 tactic: Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	StreamableHTTPServerTransport deployment with single McpServer/Server instance shared across multiple authenticated client connections. Requires PR:L (authenticated user access). Affects MCP TypeScript SDK versions 1.10.0–1.25.3.
Impact	CVSS 7.1 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None.
Exploit ScenarioDerived	An attacker could exploit this vulnerability to compromise the affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. [CVSS 7.1 HIGH]

RemediationAI

Fixed in version 1.26.0.. Restrict network access to the affected service where possible.

Affected Packages

npm @modelcontextprotocol/sdk fix: 1.26.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in npm

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-362 (Race Condition). 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.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (github) PRIMARY 7.1 HIGH

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

Red Hat 7.1 HIGH

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

CVE Published

Feb 04, 2026 - 22:15 nvd

HIGH 7.1

DescriptionCVE.org

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.

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

7 npm packages depend on @modelcontextprotocol/sdk (7 direct, 0 indirect)

Ecosystem-wide dependent count for version 1.10.0.

Executive ViewAI

Why It Matters

CVE-2026-25536 is a HIGH severity vulnerability in the MCP TypeScript SDK that could allow attackers to compromise systems using this component. Organizations running MCP servers or clients are at risk until a patch becomes available. Immediate inventory and containment measures are required to prevent potential exploitation.

Business Impact: High

Compensating Controls

Isolate affected MCP TypeScript SDK instances to restricted network segments with egress filtering. Implement enhanced logging and monitoring on all MCP communications. Restrict API access through strong authentication and API gateway controls. Consider disabling MCP functionality if not business-critical. Monitor vendor channels closely for patch availability. Disable unused features and minimize SDK exposure in production environments.

Threat Intelligence Overview

EPSS Score

0.0%

Top 98% exploitable

Exploit

POC

Public exploit code exists

Data Quality

6 sources

Confidence: High

NVD

CVE.org

EPSS Vendor

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC Yes

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +36

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Race Condition MEDIUM

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).