CVE-2026-9739 json
MCP Toolbox for Databases vulnerable to DNS rebinding attacks
published 2026-05-27 5 mo ago modified 2026-10-26 13 d ago also GHSA-7pf3-8xx7-rvhf , GO-2026-5870 , EUVD-2026-32672
- cvss
- 9.4
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 20%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- go github.com/googleapis/mcp-toolbox 1.2.0
- Google MCP Toolbox for Databases PR 3054 (Fix CORS bypass)
- govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
opensuse advisories openSUSE-SU-2026:21483-1
- github.com/googleapis/mcp-toolbox@c4c7bd9 commit
- github.com/googleapis/mcp-toolbox#3054 pull request
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 5 mo ago
Exploit prediction
0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.4 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H |
| CNA | 4.0 | 9.4 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| go | github.com/googleapis/mcp-toolbox | <1.2.0 |
1.2.0 |
Affected products
- Google MCP Toolbox for Databases
Classification
- Weakness
-
- CWE-942 Permissive Cross-domain Security Policy with Untrusted Domains
References
-
github.com
/googleapis/mcp-toolbox/pull/3054
web, patch
-
github.com
/googleapis/mcp-toolbox/commit/c4c7bd917e686de68e2be866cfe3872c3439efae
web, patch
-
github.com
/googleapis/mcp-toolbox/issues/3053
web, report
-
nvd.nist.gov
/vuln/detail/CVE-2026-9739
advisory
-
github.com
/googleapis/mcp-toolbox
package
-
github.com
/advisories/GHSA-7pf3-8xx7-rvhf
advisory
Sources
- CVE List CVE-2026-9739
- GitHub Advisory GHSA-7pf3-8xx7-rvhf
- NVD CVE-2026-9739
- OSV GO-2026-5870
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.