01 Record

CVE-2026-53937

MCP Kotlin SDK's unbounded line buffer in StdioServerTransport/StdioClientTransport leads to memory exhaustion (DoS)

MediumPUBLISHEDCNA: GitHub_M

CNA base score6.2 CVSS v3.xCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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02 Description

MCP Kotlin SDK's unbounded line buffer in StdioServerTransport/StdioClientTransport leads to memory exhaustion (DoS)

03 Exploitation and scoring

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.
AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
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

0.18% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 7.7% of scored records. A rank, not a probability.

NVD base score

6.2 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Awaiting Analysis. NVD last modified this record on 2026-09-14.

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.