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CVE-2026-108859— mcp-go through 1.2.1 Denial of Service via Unbounded POST Body Buffering

Quick assessment

Affected
mark3labs mcp-go
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

mcp-go 1.2.1 版本存在一个拒绝服务（DoS）漏洞，位于 StreamableHTTPServer.ServeHTTP 中。该漏洞允许远程未认证的攻击者通过发送过大的 POST 请求体来耗尽服务器内存。攻击者可发送任意大小或大量并发的 POST 请求，这些请求在被验证前会通过 io.ReadAll 完全读取到内存中，从而导致服务器性能下降或引发内存溢出（OOM），最终杀死服务器进程。

CVSS 7.5 · High EPSS 0.55% · P44

Affected Version Matrix 1

VendorProduct Version RangeStatus
mark3labs mcp-go ≤ 1.2.1 affected
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I. Basic Information for CVE-2026-108859

Vulnerability Information
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Vulnerability Title
mcp-go through 1.2.1 Denial of Service via Unbounded POST Body Buffering
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
mark3labs mcp-go 0 ~ 1.2.1 -

II. Public POCs for CVE-2026-108859

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III. Intelligence Information for CVE-2026-108859

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Vendor Advisories for CVE-2026-108859 (1)

News Coverage for CVE-2026-108859 (1)

IV. Related Vulnerabilities

Same product: mcp-go
Same vendor: mark3labs
Same weakness: CWE-770

V. Comments for CVE-2026-108859

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