CVE-2026-108859
HIGHCVSS 7.5Description
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.
Timeline
Published:October 11th, 2026 2:17 PM
Last modified:October 18th, 2026 12:17 PM
CVSS Scoring
CVSS v3: 7.5 (HIGH)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weaknesses (CWE)
References & Reports
Advisories, patches, and third-party reports
- 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
Source: NIST NVD · Data may lag official sources by up to one minute