All vulnerabilities
CVE-2026-108859

mcp-go through 1.2.1 Denial of Service via Unbounded POST Body Buffering

mark3labs mcp-go
Open in ThreatlineRecord JSON
CVSS
8.7High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.55%Chance of exploitation activity in the next 30 days, higher than 44% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published11 Oct 2026Updated 18 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Description

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.

Text from CVE List

Affected versions 1

  • mcp-goaffected: all versions through 1.2.1CVE List

References 4