GHSA-FVH2-GM75-J4J7
Vulnerability from github – Published: 2026-05-18 17:00 – Updated: 2026-05-18 17:00Summary
dynoxide's MCP HTTP transport was vulnerable to DNS rebinding via its transitive rmcp dependency, plus a related cross-origin CSRF gap. A malicious web page could make the user's browser send requests to a local dynoxide mcp --http or dynoxide serve --mcp server with a non-loopback Host header, which the server would then process. Affects 0.9.3 to 0.9.12. The stdio transport (dynoxide mcp without --http, which is the default) is not affected.
Impact
If a user is running dynoxide mcp --http (or dynoxide serve --mcp) on their machine and then visits a malicious web page, the attacker's JavaScript can call any MCP tool exposed by the running dynoxide instance.
Reachable tools include reads (get_item, query, scan, batch_get_item, describe_table, list_tables) and writes (put_item, update_item, delete_item, create_table, batch_write_item).
Any data in tables that the local dynoxide instance has access to can be read, modified, or destroyed.
Patches
dynoxide 0.9.13 closes both the named CVE and a related cross-origin CSRF gap:
-
DNS rebinding (the named CVE).
rmcpis upgraded from 1.1.1 to 1.6.0. rmcp 1.4+ ships a default Host-header allowlist (["localhost", "127.0.0.1", "::1"]) which rejects requests carrying any other Host header with a 403. -
Defence in depth. Explicit
allowed_hostsandallowed_originslists are now set onStreamableHttpServerConfigdirectly. The Host allowlist protects against a future rmcp default flip. The Origin allowlist closes a related cross-origin CSRF gap that the Host check alone does not address: a malicious page couldfetchthe loopback endpoint withmode: 'no-cors', the Host header would match (it's the literal loopback address the browser is connecting to), but the Origin header would otherwise have been unchecked.
Native MCP clients that don't send an Origin header (Claude Code, Cursor, the dynoxide CLI) are unaffected by the Origin check and continue to work.
Workarounds
- Upgrade to dynoxide 0.9.13.
- If upgrade is not immediately possible: do not run the MCP HTTP transport. Run
dynoxide mcp(stdio, the default) instead ofdynoxide mcp --http, and don't pass--mcptodynoxide serve.
Resources
- Upstream rmcp advisory: GHSA-89vp-x53w-74fx
- Upstream CVE: CVE-2026-42559
- dynoxide release: v0.9.13
- MCP transport security guidance: https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#security-warning
Credits
Vulnerability identified via GitHub Dependabot alert on the transitive rmcp dependency.
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "dynoxide-rs"
},
"ranges": [
{
"events": [
{
"introduced": "0.9.3"
},
{
"fixed": "0.9.13"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "npm",
"name": "dynoxide"
},
"ranges": [
{
"events": [
{
"introduced": "0.9.3"
},
{
"fixed": "0.9.13"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-346",
"CWE-350",
"CWE-352"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-18T17:00:25Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "## Summary\n\ndynoxide\u0027s MCP HTTP transport was vulnerable to DNS rebinding via its transitive `rmcp` dependency, plus a related cross-origin CSRF gap. A malicious web page could make the user\u0027s browser send requests to a local `dynoxide mcp --http` or `dynoxide serve --mcp` server with a non-loopback `Host` header, which the server would then process. Affects 0.9.3 to 0.9.12. The stdio transport (`dynoxide mcp` without `--http`, which is the default) is not affected.\n\n## Impact\n\nIf a user is running `dynoxide mcp --http` (or `dynoxide serve --mcp`) on their machine and then visits a malicious web page, the attacker\u0027s JavaScript can call any MCP tool exposed by the running dynoxide instance.\n\nReachable tools include reads (`get_item`, `query`, `scan`, `batch_get_item`, `describe_table`, `list_tables`) and writes (`put_item`, `update_item`, `delete_item`, `create_table`, `batch_write_item`).\n\nAny data in tables that the local dynoxide instance has access to can be read, modified, or destroyed.\n\n## Patches\n\ndynoxide 0.9.13 closes both the named CVE and a related cross-origin CSRF gap:\n\n1. **DNS rebinding (the named CVE).** `rmcp` is upgraded from 1.1.1 to 1.6.0. rmcp 1.4+ ships a default Host-header allowlist (`[\"localhost\", \"127.0.0.1\", \"::1\"]`) which rejects requests carrying any other Host header with a 403.\n\n2. **Defence in depth.** Explicit `allowed_hosts` and `allowed_origins` lists are now set on `StreamableHttpServerConfig` directly. The Host allowlist protects against a future rmcp default flip. The Origin allowlist closes a related cross-origin CSRF gap that the Host check alone does not address: a malicious page could `fetch` the loopback endpoint with `mode: \u0027no-cors\u0027`, the Host header would match (it\u0027s the literal loopback address the browser is connecting to), but the Origin header would otherwise have been unchecked.\n\nNative MCP clients that don\u0027t send an Origin header (Claude Code, Cursor, the dynoxide CLI) are unaffected by the Origin check and continue to work.\n\n## Workarounds\n\n- Upgrade to dynoxide 0.9.13.\n- If upgrade is not immediately possible: do not run the MCP HTTP transport. Run `dynoxide mcp` (stdio, the default) instead of `dynoxide mcp --http`, and don\u0027t pass `--mcp` to `dynoxide serve`.\n\n## Resources\n\n- Upstream rmcp advisory: [GHSA-89vp-x53w-74fx](https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx)\n- Upstream CVE: [CVE-2026-42559](https://www.cve.org/CVERecord?id=CVE-2026-42559)\n- dynoxide release: [v0.9.13](https://github.com/nubo-db/dynoxide/releases/tag/v0.9.13)\n- MCP transport security guidance: \u003chttps://modelcontextprotocol.io/specification/2025-11-25/basic/transports#security-warning\u003e\n\n## Credits\n\nVulnerability identified via GitHub Dependabot alert on the transitive rmcp dependency.",
"id": "GHSA-fvh2-gm75-j4j7",
"modified": "2026-05-18T17:00:25Z",
"published": "2026-05-18T17:00:25Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nubo-db/dynoxide/security/advisories/GHSA-fvh2-gm75-j4j7"
},
{
"type": "PACKAGE",
"url": "https://github.com/nubo-db/dynoxide"
},
{
"type": "WEB",
"url": "https://github.com/nubo-db/dynoxide/releases/tag/v0.9.13"
},
{
"type": "WEB",
"url": "https://rustsec.org/advisories/RUSTSEC-2026-0140.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "dynoxide: DNS rebinding and cross-origin CSRF via MCP HTTP transport"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.