CVE-2026-67432: modelcontextprotocol ruby-sdk · Unthrottled Resource Allocation
Affects modelcontextprotocol ruby-sdkSource CVE Database V5
Not known to be exploited · CVSS 7.5 High : upgrade to 0.23.0 soon.
Data as of 28 Oct 2026, 05:11 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 55% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.23.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 29 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade ruby-sdk and mcp to 0.23.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| modelcontextprotocolruby-sdk | Affected
| Fixed in
|
RubyGemsmcppkg:gem/mcpOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade to MCP Ruby SDK version 0.23.0 or later, where this vulnerability is fixed by imposing size limits on JSON-RPC POST bodies. Patch status is confirmed by the vendor advisory stating the fix in version 0.23.0. Until upgraded, consider implementing external request size limits or filtering to mitigate potential attacks.
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.