RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport
Published May 14, 2026
8.8
HIGHCVSS 3.1
EPSS 0.24%
Description
RMCP is an official Rust SDK for the Model Context Protocol. Prior to version 1.4.0, the rmcp crate's Streamable HTTP server transport (crates/rmcp/src/transport/streamable_http_server/) did not validate the incoming Host header. This allowed a malicious public website, via a DNS rebinding attack, to send authenticated requests to an MCP server running on the victim's loopback or private-network interface. This vulnerability is fixed in 1.4.0.
Affected products
-
- Version < 1.4.0StatusaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Modelcontextprotocol | Rust-Sdk | n/a |
|
No data.
No data.
No Red Hat product state for this CVE.
dynoxide-rs
crates.io
Introduced 0.9.3 Fixed 0.9.13dynoxide
npm
Introduced 0.9.3 Fixed 0.9.13
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| crates.io | dynoxide-rs | 0.9.3 | 0.9.13 |
| npm | dynoxide | 0.9.3 | 0.9.13 |
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
TotalDecision
n/aAssessed May 14, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
May–Oct 2026- EPSS v4
- EPSS v5
Percentile over time
- EPSS v4
- EPSS v5
Table of values (3 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.24% (0.00242) | 13.93th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.21% (0.00213) | 11.49th | v5 (v2026.06.15) |
| May 15, 2026 | 0.02% (0.00018) | 4.81th | v4 (v2025.03.14) |
References (10)
- https://github.com/advisories/GHSA-89vp-x53w-74fx Advisory
- https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c11cd89bf15fa90d3 x_refsource_MISC
- https://github.com/modelcontextprotocol/rust-sdk/issues/815 x_refsource_MISC
- https://github.com/modelcontextprotocol/rust-sdk/issues/822 x_refsource_MISC
- https://github.com/modelcontextprotocol/rust-sdk/pull/764 x_refsource_MISC
- https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x53w-74fx x_refsource_CONFIRM
- https://github.com/nubo-db/dynoxide/security/advisories/GHSA-fvh2-gm75-j4j7
- https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#security-warning
- https://nvd.nist.gov/vuln/detail/CVE-2026-42559
- https://rustsec.org/advisories/RUSTSEC-2026-0140.html
Change history (0)
No recorded changes yet.