mcp-go through 1.2.1 Denial of Service via Unbounded POST Body Buffering
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.
CVE-2026-108859
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-108859
mcp-go
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://github.com/mark3labs/mcp-go",
"vendor": "mark3labs",
"product": "mcp-go",
"versions": [
{
"status": "affected",
"version": "0",
"versionType": "semver",
"lessThanOrEqual": "1.2.1"
}
],
"packageURL": "pkg:golang/github.com/mark3labs/mcp-go",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-108859
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #34651 · Revision 1
- Added to Heist Feed
- Publisher date