CVE-2026-53957 Contentful MCP Server: export_space/import_space tools pass LLM-controlled `host`/`proxy` args to CMA client, redirecting server PAT to attacker-controlled endpoint
Attackers can redirect API requests to malicious hosts via LLM-controlled arguments, stealing Contentful management tokens and gaining persistent access to spaces.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53957?
CVE-2026-53957 is a high-severity server-side request forgery vulnerability in @contentful contentful-mcp-server, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Contentful MCP Server is a Model Context Protocol server for the Contentful Management API. Prior to @contentful/mcp-server 1.7.19 and @contentful/mcp-tools 0.4.5, export_space and import_space in packages/mcp-tools/src/tools/jobs/space-to-space-migration/exportSpace.ts and packages/mcp-tools/src/tools/jobs/space-to-space-migration/importSpace.ts expose host, proxy, rawProxy, and insecure network options to LLM-controlled tool arguments and combine those options with the server's CONTENTFUL_MANAGEMENT_TOKEN. After space_to_space_migration_handler enables the migration tools, a direct MCP call or prompt injection through attacker-controlled Contentful content can redirect Contentful Management API requests and their Authorization header to an attacker-controlled host or proxy. The regular tools that use createToolClient are unaffected because those tools pin the host from server configuration. Exposure of the personal access token permits persistent out-of-band access to every Contentful space within the token's scope. This issue is fixed in @contentful/mcp-server 1.7.19 and @contentful/mcp-tools 0.4.5.
Weakness: CWE-918
Which versions are affected by CVE-2026-53957?
4 open source packages ship an affected version, including @contentful/mcp-server and @contentful/mcp-tools.
| Package | Affected | Fixed in |
|---|---|---|
@contentful/mcp-server npm | All versions | 1.7.19 |
@contentful/mcp-server npm | All versions | 1.7.19 |
@contentful/mcp-tools npm | All versions | 0.4.5 |
@contentful/mcp-tools npm | All versions | 0.4.5 |
How do I fix CVE-2026-53957?
Upgrade @contentful/mcp-server to 1.7.19 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-53957 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53957 exists.
Sources
Also known as GHSA-2xhg-73j7-rrgx.