High severity · published Feb 4, 2026
CVE-2026-25536
@modelcontextprotocol/sdk has cross-client data leak via shared server/transport instance reuse
7.1
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 22% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TY
typescript-sdk · modelcontextprotocol
>= 1.10.0, < 1.26.0 · source: vendor
MT
Mcp Typescript Sdk · Lfprojects
1.10.0 before 1.26.0 · source: NVD
RH
Red Hat Ansible Automation Platform 2.6 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-25536
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-25536
Issue Tracking
https://github.com/modelcontextprotocol/typescript-sdk/issues/204
Issue Tracking
https://github.com/modelcontextprotocol/typescript-sdk/issues/243
Mitigation
https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-345p-7cg4-v4c7
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:3960
access.redhat.com
https://access.redhat.com/security/cve/CVE-2026-25536
bugzilla.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2436937
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