CVE-2026-108395: DoS (CVSS 7.5)

Description

The Model Context Protocol Java SDK is the official Java SDK for Model Context Protocol servers and clients. From version 0.8.0 through 0.12.0 in the io.modelcontextprotocol.sdk:mcp artifact, from 0.13.0 through 0.18.3 and 1.0.0 through 1.1.3 in io.modelcontextprotocol.sdk:mcp-core, and from mcp-core 2.0.0-M1 through 2.0.0, the Servlet-based SSE, Streamable HTTP, and Stateless server transports read an HTTP request body into memory without enforcing a maximum size. An unauthenticated remote client able to reach an affected transport can stream an arbitrarily large POST body, including with chunked transfer encoding, until the Java process exhausts its heap and becomes unavailable. Authentication, Origin or Host validation, or an upstream request-size limit can reject the request before the vulnerable read. The maintained mcp-core lines are fixed in versions 0.18.4, 1.1.4, and 2.0.1.

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CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0061

Probability of exploitation

0.48%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-770 CWE-770

References

Other References

https://github.com/modelcontextprotocol/java-sdk/commit/1499df22c7023aa257223143a5dcf5b1db7ef80d https://github.com/modelcontextprotocol/java-sdk/commit/6a41dedaa0625551582d8247e5a4d78eae1131b2 https://github.com/modelcontextprotocol/java-sdk/commit/8c0fdd1b1f76adba3ce7945d29f73fa2ddc66598 https://github.com/modelcontextprotocol/java-sdk/commit/9e4d5fa827b6ba69457f5fd93573184789528efa https://github.com/modelcontextprotocol/java-sdk/releases/tag/v0.18.4 https://github.com/modelcontextprotocol/java-sdk/releases/tag/v1.1.4 https://github.com/modelcontextprotocol/java-sdk/releases/tag/v2.0.1 https://github.com/modelcontextprotocol/java-sdk/security/advisories/GHSA-4x8c-5vv7-973f

Frequently Asked Questions

What is CVE-2026-108395? +

The Model Context Protocol Java SDK is the official Java SDK for Model Context Protocol servers and clients. From version 0.8.0 through 0.12.0 in the io.modelcontextprotocol.sdk:mcp artifact, from 0.13.0 through 0.18.3 and 1.0.0 through 1.1.3 in io.modelcontextprotocol.sdk:mcp-core, and from mcp-core 2.0.0-M1 through 2.0.0, the Servlet-based SSE, Streamable HTTP, and Stateless server transports read an HTTP request body into memory without enforcing a maximum size. An unauthenticated remote client able to reach an affected transport can stream an arbitrarily large POST body, including with chunked transfer encoding, until the Java process exhausts its heap and becomes unavailable. Authentication, Origin or Host validation, or an upstream request-size limit can reject the request before the vulnerable read. The maintained mcp-core lines are fixed in versions 0.18.4, 1.1.4, and 2.0.1. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-108395? +

CVE-2026-108395 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0061, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-108395? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-108395