CVE-2026-33946

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.46% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 38.2% of scored records. A rank, not a probability.

NVD base score

8.2 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-03-27 21:20Z5 MO AGO

Last updated

2026-03-30 18:42Z5 MO AGO

Reserved

2026-03-24

Assigning CNA

GitHub_M

Record state

PUBLISHED

Severity

High (CVSS 8.2)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Weaknesses

• CWE-384Session FixationCompound
• CWE-639Authorization Bypass Through User-Controlled KeyBase

Data version

5.2

Document digest

a88d475a165622c1e6407ffc33ca293e0db4d2cb38ebd99dfd1a8d0ae0172644

• github.comhttps://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-qvqr-5cv7-wh35x_refsource_CONFIRM
• github.comhttps://github.com/modelcontextprotocol/ruby-sdk/commit/db40143402d65b4fb6923cec42d2d72cb89b3874x_refsource_MISC
• hackerone.comhttps://hackerone.com/reports/3556146x_refsource_MISC
• github.comhttps://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.AspNetCore/SseHandler.cs#L93-L97x_refsource_MISC
• github.comhttps://github.com/modelcontextprotocol/go-sdk/blob/main/mcp/streamable.go#L281C1-L288C2x_refsource_MISC
• github.comhttps://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/streamable_http.py#L680-L685x_refsource_MISC
• github.comhttps://github.com/modelcontextprotocol/ruby-sdk/blob/main/examples/streamable_http_server.rbx_refsource_MISC
• github.comhttps://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.9.2x_refsource_MISC