How severe is CVE-2026-59971?

CVE-2026-59971 has a CVSS score of 10/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-59971?

CVE-2026-59971 affects the following packages: mysql-mcp-server (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-59971?

Update mysql-mcp-server to 0.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59971 is resolved across your whole dependency graph.

How do I detect CVE-2026-59971 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mysql-mcp-server. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-59971 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-59971?

O3 pinpoints whether CVE-2026-59971 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-59971 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-59971 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was CVE-2026-59971 published, and has it been updated?

CVE-2026-59971 was published on September 11, 2026 and was last updated on September 11, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

CRITICAL severity

CVE-2026-59971

CRITICAL

CVE-2026-59971 is a critical-severity (CVSS 10) remote code execution vulnerability in mysql-mcp-server. O3 Security confirms whether CVE-2026-59971 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

MySQL MCP Server: Missing Origin/Host Validation in SSE Transport Enables Unauthenticated SQL Execution (DNS Rebinding / Direct Exposure)

Published

Sep 11, 2026

Updated

Sep 11, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 11, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

🐍mysql-mcp-server

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

In SSE/HTTP transport mode, mysql_mcp_server constructs SseServerTransport without passing security_settings. As a result, the MCP Python SDK's DNS-rebinding protection (Origin/Host header validation) is disabled; the Starlette application has no CORS or TrustedHost middleware; and the service binds to 0.0.0.0 by default with no authentication on any route.

Trigger condition: MCP_TRANSPORT=sse. The default stdio mode is not affected.

Attack Scenarios

Scenario A — Direct exposure: Any network attacker can invoke execute_sql to run arbitrary SQL without credentials → full data dump, and via MySQL FILE privileges, arbitrary file read/write and RCE.

Scenario B — DNS rebinding (local bind): An attacker lures a victim's browser to a malicious page, rebinds their domain to 127.0.0.1, and uses the browser as a proxy to invoke execute_sql as same-origin.

Root Cause

In src/mysql_mcp_server/server.py:

SseServerTransport is constructed without security_settings — the SDK defaults enable_dns_rebinding_protection to False.
The Starlette app has no CORS or TrustedHost middleware.
All three routes (/, /sse, /messages/) are unauthenticated.
The service binds to 0.0.0.0 by default.
The sink is cursor.execute(query) with a fully attacker-controlled query.

Impact

Unauthenticated arbitrary SQL execution against the configured database
Full data exfiltration and modification
If the MySQL account holds FILE privilege: arbitrary file read (LOAD_FILE) and write (INTO OUTFILE) — potential RCE via webshell drop
Internet-wide scanning has identified 25 publicly reachable SSE instances of this project

Fix

Released in v0.4.2: DNS-rebinding protection is now enabled by passing TransportSecuritySettings(enable_dns_rebinding_protection=True) to SseServerTransport, and the documented recommended bind address is 127.0.0.1.

Credits

Discovered by Huanchen, SongWu (JHU), and BrookeYangRui (JHU).

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`mysql-mcp-server`	all versions	0.4.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mysql-mcp-server. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update mysql-mcp-server to 0.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59971 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-59971 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-59971. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary In SSE/HTTP transport mode, `mysql_mcp_server` constructs `SseServerTransport` without passing `security_settings`. As a result, the MCP Python SDK's DNS-rebinding protection (Origin/Host header validation) is disabled; the Starlette application has no CORS or TrustedHost middleware; and the service binds to `0.0.0.0` by default with no authentication on any route. **Trigger condition:** `MCP_TRANSPORT=sse`. The default stdio mode is not affected. ## Attack Scenarios **Scenario A — Direct exposure:** Any network attacker can invoke `execute_sql` to run arbitrary SQL without cred

O3 Security · Impact-Aware SCA

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