CVE-2026-67431

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Source
https://cve.org/CVERecord?id=CVE-2026-67431
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-67431.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-67431
Aliases
Published
2026-07-29T19:15:32.340Z
Modified
2026-08-12T03:51:12.865038282Z
Severity
  • 8.3 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N CVSS Calculator
Summary
MCP Ruby SDK: Ruby SSE Session Poisoning
Details

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.

Database specific 
{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-284"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/67xxx/CVE-2026-67431.json"
}
References

Affected packages

Git / github.com/modelcontextprotocol/ruby-sdk

Affected ranges

Type
GIT
Repo
https://github.com/modelcontextprotocol/ruby-sdk
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
35466605319a34e4c7808712ae9bb1ca1afb2356
Fixed
95feef2dcfba25d92a8963d14b7a3b279122f36f
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "0.23.0"
        }
    ],
    "source": [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

v0.*
v0.1.0
v0.10.0
v0.11.0
v0.12.0
v0.13.0
v0.14.0
v0.15.0
v0.16.0
v0.17.0
v0.18.0
v0.19.0
v0.2.0
v0.20.0
v0.21.0
v0.22.0
v0.3.0
v0.4.0
v0.5.0
v0.6.0
v0.7.0
v0.7.1
v0.8.0
v0.9.0
v0.9.1
v0.9.2

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-67431.json"