Google MCP Toolbox for Databases up to 2024-11-05 SSE Initialization cross-domain policy

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.0$0-$5k0.00

Summaryinfo

A vulnerability was found in Google MCP Toolbox for Databases up to 2024-11-05. It has been classified as critical. Affected by this vulnerability is an unknown functionality of the component SSE Initialization Handler. This manipulation causes cross-domain policy. This vulnerability appears as CVE-2026-9739. The attack may be initiated remotely. There is no available exploit. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability classified as critical was found in Google MCP Toolbox for Databases up to 2024-11-05. Affected by this vulnerability is an unknown code block of the component SSE Initialization Handler. The manipulation with an unknown input leads to a cross-domain policy vulnerability. The CWE definition for the vulnerability is CWE-942. The product uses a cross-domain policy file that includes domains that should not be trusted. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-9739 since 05/27/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/28/2026).

Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross-domain policy
CWE: CWE-942 / CWE-346 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: github.com

Timelineinfo

05/27/2026 CVE reserved
05/28/2026 +1 days Advisory disclosed
05/28/2026 +0 days VulDB entry created
05/28/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: google.com

Advisory: 3053
Status: Confirmed

CVE: CVE-2026-9739 (🔒)
GCVE (CVE): GCVE-0-2026-9739
GCVE (VulDB): GCVE-100-366553

Entryinfo

Created: 05/28/2026 05:26
Changes: 05/28/2026 05:26 (68)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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