CVE-2026-108859

mcp-go through 1.2.1 contains a denial of service vulnerability in StreamableHTTPServer.ServeHTTP that allows remote unauthenticated attackers to exhaust memory by sending oversized POST bodies. Attackers can send arbitrarily large or many concurrent POST requests, read fully via io.ReadAll before validation, to degrade or OOM-kill the server process.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/mark3labs/mcp-go
https://github.com/mark3labs/mcp-go/blob/90d247ed8d45cbb7d71d9a95e112789b78760443/server/streamable_http.go#L405-L411
https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/mark3labs-mcp-go-streamable-http-unbounded-body
https://www.vulncheck.com/advisories/mcp-go-through-1.2.1-denial-of-service-via-unbounded-post-body-buffering

Configurations

No configuration.

History

11 Oct 2026, 14:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-11 14:17

Updated : 2026-10-18 12:17

NVD link : CVE-2026-108859

Mitre link : CVE-2026-108859

CVE.ORG link : CVE-2026-108859

JSON object : View

Products Affected

No product.

CWE

CWE-770

Allocation of Resources Without Limits or Throttling

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