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12 vulnerabilities found for ruby-sdk by modelcontextprotocol
CVE-2026-67432 (GCVE-0-2026-67432)
Vulnerability from nvd – Published: 2026-07-29 19:17 – Updated: 2026-07-29 19:34
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-67431 (GCVE-0-2026-67431)
Vulnerability from nvd – Published: 2026-07-29 19:15 – Updated: 2026-07-30 14:35
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Ruby SSE Session Poisoning
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not bind a session ID to a session owner, allowing an attacker with a stolen session ID to send tools/call requests that execute in the victim's session. This issue is fixed in version 0.23.0.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
- CWE-284 - Improper Access Control
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-67430 (GCVE-0-2026-67430)
Vulnerability from nvd – Published: 2026-07-29 19:10 – Updated: 2026-07-30 15:19
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Unbounded session retention in StreamableHTTPTransport allows memory exhaustion via initialize flood
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not expire sessions by default, so repeated initialize requests retain unbounded ServerSession objects and can exhaust process memory. This issue is fixed in version 0.23.0.
Severity
5.3 (Medium)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-63119 (GCVE-0-2026-63119)
Vulnerability from nvd – Published: 2026-07-29 19:12 – Updated: 2026-07-29 19:28
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StdioTransport and MCP::Client::Stdio in the mcp gem use IO#gets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This issue is fixed in version 0.23.0.
Severity
6.2 (Medium)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-63118 (GCVE-0-2026-63118)
Vulnerability from nvd – Published: 2026-07-29 19:07 – Updated: 2026-07-29 19:35
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not validate the HTTP Host or Origin request headers, which allows a malicious browser page to use DNS rebinding to reach a locally running MCP server and invoke exposed tools. This issue is fixed in version 0.23.0.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
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CVE-2026-33946 (GCVE-0-2026-33946)
Vulnerability from nvd – Published: 2026-03-27 21:20 – Updated: 2026-03-30 18:42
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to version 0.9.2, the Ruby SDK's streamable_http_transport.rb implementation contains a session hijacking vulnerability. An attacker who obtains a valid session ID can completely hijack the victim's Server-Sent Events (SSE) stream and intercept all real-time data. Version 0.9.2 contains a patch.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
8 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://hackerone.com/reports/3556146 | x_refsource_MISC |
| https://github.com/modelcontextprotocol/csharp-sd… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/go-sdk/bl… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/python-sd… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.9.2
|
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CVE-2026-67432 (GCVE-0-2026-67432)
Vulnerability from cvelistv5 – Published: 2026-07-29 19:17 – Updated: 2026-07-29 19:34
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-67431 (GCVE-0-2026-67431)
Vulnerability from cvelistv5 – Published: 2026-07-29 19:15 – Updated: 2026-07-30 14:35
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Ruby SSE Session Poisoning
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not bind a session ID to a session owner, allowing an attacker with a stolen session ID to send tools/call requests that execute in the victim's session. This issue is fixed in version 0.23.0.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
- CWE-284 - Improper Access Control
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-63119 (GCVE-0-2026-63119)
Vulnerability from cvelistv5 – Published: 2026-07-29 19:12 – Updated: 2026-07-29 19:28
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Unbounded line buffer in stdio transports leads to memory exhaustion (DoS)
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StdioTransport and MCP::Client::Stdio in the mcp gem use IO#gets without a byte limit, allowing a peer that sends data without a newline to exhaust process memory. This issue is fixed in version 0.23.0.
Severity
6.2 (Medium)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-67430 (GCVE-0-2026-67430)
Vulnerability from cvelistv5 – Published: 2026-07-29 19:10 – Updated: 2026-07-30 15:19
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Unbounded session retention in StreamableHTTPTransport allows memory exhaustion via initialize flood
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not expire sessions by default, so repeated initialize requests retain unbounded ServerSession objects and can exhaust process memory. This issue is fixed in version 0.23.0.
Severity
5.3 (Medium)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-63118 (GCVE-0-2026-63118)
Vulnerability from cvelistv5 – Published: 2026-07-29 19:07 – Updated: 2026-07-29 19:35
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Streamable HTTP transport lacks DNS-rebinding (Host/Origin) protection
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not validate the HTTP Host or Origin request headers, which allows a malicious browser page to use DNS rebinding to reach a locally running MCP server and invoke exposed tools. This issue is fixed in version 0.23.0.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.23.0
|
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CVE-2026-33946 (GCVE-0-2026-33946)
Vulnerability from cvelistv5 – Published: 2026-03-27 21:20 – Updated: 2026-03-30 18:42
VLAI
EPSS
VEX
Title
MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay
Summary
MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to version 0.9.2, the Ruby SDK's streamable_http_transport.rb implementation contains a session hijacking vulnerability. An attacker who obtains a valid session ID can completely hijack the victim's Server-Sent Events (SSE) stream and intercept all real-time data. Version 0.9.2 contains a patch.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
8 references
| URL | Tags |
|---|---|
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_CONFIRM |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://hackerone.com/reports/3556146 | x_refsource_MISC |
| https://github.com/modelcontextprotocol/csharp-sd… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/go-sdk/bl… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/python-sd… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
| https://github.com/modelcontextprotocol/ruby-sdk/… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| modelcontextprotocol | ruby-sdk |
Affected:
< 0.9.2
|
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"name": "https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.9.2",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.9.2"
}
],
"source": {
"advisory": "GHSA-qvqr-5cv7-wh35",
"discovery": "UNKNOWN"
},
"title": "MCP Ruby SDK: Insufficient Session Binding Allows SSE Stream Hijacking via Session ID Replay"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-33946",
"datePublished": "2026-03-27T21:20:07.900Z",
"dateReserved": "2026-03-24T19:50:52.105Z",
"dateUpdated": "2026-03-30T18:42:43.387Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}