9.4

CVE-2026-9739: google mcp_toolbox_for_databases

CVSS: 9.4v4.0CriticalAwaiting analysis
AliasesGHSA-7pf3-8xx7-rvhfGO-2026-5870
Published 27-05-2026Last modified 28-05-2026
Open JSON

Vulnerability summary

CVE-2026-9739 is a critical (CVSS 9.4) vulnerability in google mcp_toolbox_for_databases. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 13.7% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.4/10
010
Critical · v4.0 (CVE.org)
EPSS score
0.24%
0%100%
Low · -0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:21483-1

Timeline

  1. 27-05-2026
    PublishedVulnerability first disclosed.
  2. 28-05-2026
    Last modifiedVulnerability information updated.

Description

Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented `allowed-origins` and `allowed-hosts` flags to align with MCP security guidelines. However, the hardcoded `Access-Control-Allow-Origin: *` header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.24%

Chance of exploitation in the next 30 days

Percentile

14%

Versus all other CVEs

30-day change

-0.04 pp

From 0.28% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.24%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Github.com/googleapis1 product
  • mcp-toolbox< 1.2.0
Google1 product

2 vendors · 2 products

References

6 links