High severity · published Jul 31, 2026
CVE-2026-14539
Denial of Service via Unrestricted Payload Buffering in MCP Toolbox
7.5
CVSS
0.2%
EPSS
No
On KEV
Description
An allocation of resources without limits vulnerability in the HTTP handler component of Google mcp-toolbox versions up to and including 1.4.0 allows an unauthenticated attacker to cause a denial of service (DoS). The /mcp endpoint handler reads incoming payloads directly into system memory using an unrestricted buffer loop (io.ReadAll) without applying defensive constraints such as http.MaxBytesReader or pre-read Content-Length enforcement. By submitting a single, massive HTTP request body, an attacker can linearly consume available host memory until the runtime process is terminated by an Out-Of-Memory (OOM) error.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 15% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MC
mcp-toolbox · Google
0.0.0 through 1.4.0 · source: vendor
MT
Mcp Toolbox For Databases · Google
before 1.5.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-14539
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-14539
Issue Tracking
https://github.com/googleapis/mcp-toolbox/pull/3216
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