Is CVE-2026-33946 in the CISA KEV catalog?

No. CVE-2026-33946 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-33946?

CVE-2026-33946 has a CVSS v3 base score of 5.9 (MEDIUM).

What is the EPSS score for CVE-2026-33946?

CVE-2026-33946 has an EPSS score of 0.46% (37th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-33946?

Upgrade mcp ruby sdk to 0.9.2 or later.

CVE & CISA-KEV Catalog

CVE-2026-33946

MEDIUM

5.9

CVSS v3

NVD

Description

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.

CWE-384 CWE-639Authorization Bypass Through User-Controlled Key

How to fix

Remediation Available

mcp ruby sdkNVD

Affected:< 0.9.2Fixed in:0.9.2CVE-2026-33946derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

0.46%probability of exploitation in 30 days

37thpercentile

Low risk: more likely to be exploited than 37% of all known CVEs.

References

Patch5

Exploit1

github.com

Release Notes1

github.com

Other references1

hackerone.com

Embed a live status badge for CVE-2026-33946

Markdown

[![CVE-2026-33946](https://tridentstack.com/cve/badge/CVE-2026-33946.svg)](https://tridentstack.com/cve/CVE-2026-33946)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-33946"><img src="https://tridentstack.com/cve/badge/CVE-2026-33946.svg" alt="CVE-2026-33946"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-02.