7.5

CVE-2026-67432: modelcontextprotocol ruby-sdk

CVSS: 7.5v3.1HighDeferred
AliasesGHSA-h669-8m4g-r2hc
Published 29-07-2026Last modified 29-07-2026
Open JSON

Vulnerability summary

CVE-2026-67432 is a high (CVSS 7.5) vulnerability in modelcontextprotocol ruby-sdk. EPSS estimates a 0.78% chance of exploitation in the next 30 days, higher than 55.2% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.78%
0%100%
Low · +0.35 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 29-07-2026
    PublishedVulnerability first disclosed.
  2. 29-07-2026
    Last modifiedVulnerability information updated.

Description

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 reads and parses an entire JSON-RPC POST body without a size limit, allowing an unauthenticated remote attacker to exhaust process memory. This issue is fixed in version 0.23.0.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.78%

Chance of exploitation in the next 30 days

Percentile

55%

Versus all other CVEs

30-day change

+0.35 pp

From 0.43% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.78%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Modelcontextprotocol1 product
RubyGems1 product
  • mcp< 0.23.0

2 vendors · 2 products

References

5 links