CVE-2026-67432

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 64% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
36%
KEV
Not listed

Published

July 29, 2026

Last Modified

July 30, 2026

Advisory Details (3)

Auto-updated Jul 29, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

v0.23.0

Patch available: modelcontextprotocol/ruby-sdk v0.23.0

https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0
github_commit Patch Available

commit 772e0cb1f9db (modelcontextprotocol/ruby-sdk)

Patch available: modelcontextprotocol/ruby-sdk v0.23.0 (contains commit 772e0cb1f9db)

https://github.com/modelcontextprotocol/ruby-sdk/commit/772e0cb1f9db69312006926eee59a7287ad50166
github Patch Available🟡 PoC Available

Unbounded JSON-RPC request body causes uncontrolled memory allocation in StreamableHTTPTransport · Advisory · modelcontextprotocol/ruby-sdk · GitHub

https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-h669-8m4g-r2hc

Vendor Advisories for CVE-2026-67432(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
mcp0.1.0 ... 0.9.2 (25 versions)0.23.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 53× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 23:08 UTCEG score recompute
  3. 2026-08-28 21:42 UTCEPSS rescore
  4. 2026-08-27 22:33 UTCEG score recompute
  5. 2026-08-26 23:39 UTCEG score recompute
  6. 2026-08-26 14:47 UTCEPSS rescore
  7. 2026-08-26 00:51 UTCEG score recompute
  8. 2026-08-25 13:49 UTCEPSS rescore
  9. 2026-08-24 14:40 UTCEG score recompute
  10. 2026-08-23 04:20 UTCEG score recompute
  11. 2026-08-23 00:19 UTCEPSS rescore
  12. 2026-08-22 05:33 UTCEG score recompute
  13. 2026-08-21 23:49 UTCEPSS rescore
  14. 2026-08-21 06:45 UTCEG score recompute
  15. 2026-08-20 22:56 UTCEPSS rescore
  16. 2026-08-19 20:33 UTCEG score recompute
  17. 2026-08-19 17:04 UTCEPSS rescore
  18. 2026-08-18 21:45 UTCEG score recompute
  19. 2026-08-18 13:48 UTCEPSS rescore
  20. 2026-08-17 22:33 UTCEG score recompute
  21. 2026-08-17 13:47 UTCEPSS rescore
  22. 2026-08-16 23:46 UTCEG score recompute
  23. 2026-08-16 14:56 UTCEPSS rescore
  24. 2026-08-16 12:22 UTCEG score recompute
  25. 2026-08-15 02:06 UTCEG score recompute
Show 34 more
  1. 2026-08-15 01:30 UTCEPSS rescore
  2. 2026-08-14 03:19 UTCEG score recompute
  3. 2026-08-13 22:00 UTCEPSS rescore
  4. 2026-08-12 17:09 UTCEG score recompute
  5. 2026-08-12 13:51 UTCEPSS rescore
  6. 2026-08-11 18:23 UTCEG score recompute
  7. 2026-08-11 06:58 UTCEG score recompute
  8. 2026-08-11 00:00 UTCEPSS rescore
  9. 2026-08-09 20:48 UTCEG score recompute
  10. 2026-08-09 13:47 UTCEPSS rescore
  11. 2026-08-08 22:02 UTCEG score recompute
  12. 2026-08-08 16:37 UTCEPSS rescore
  13. 2026-08-07 23:14 UTCEG score recompute
  14. 2026-08-07 00:26 UTCEG score recompute
  15. 2026-08-06 13:47 UTCEPSS rescore
  16. 2026-08-06 01:39 UTCEG score recompute
  17. 2026-08-05 19:17 UTCEPSS rescore
  18. 2026-08-05 19:17 UTCEPSS rescore
  19. 2026-08-05 01:10 UTCEG score recompute
  20. 2026-08-04 15:10 UTCEPSS rescore
  21. 2026-08-04 13:45 UTCEG score recompute
  22. 2026-08-04 10:39 UTCEPSS rescore
  23. 2026-08-03 14:57 UTCEG score recompute
  24. 2026-08-03 10:36 UTCEPSS rescore
  25. 2026-08-02 04:45 UTCEG score recompute
  26. 2026-08-02 02:27 UTCEPSS rescore
  27. 2026-08-01 05:57 UTCEG score recompute
  28. 2026-08-01 04:16 UTCEPSS rescore
  29. 2026-07-30 19:08 UTCEG score recompute
  30. 2026-07-30 16:28 UTCEPSS rescore
  31. 2026-07-29 20:19 UTCEG score recompute
  32. 2026-07-29 19:59 UTCEG score recompute
  33. 2026-07-29 19:23 UTCEG score recompute
  34. 2026-07-29 19:22 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-67432?
CVE-2026-67432 is a high vulnerability published on July 29, 2026. 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…
When was CVE-2026-67432 disclosed?
CVE-2026-67432 was first published in the National Vulnerability Database on July 29, 2026, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67432 actively exploited?
CVE-2026-67432 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 64.2% of all scored CVEs.
What is the CVSS score of CVE-2026-67432?
CVE-2026-67432 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-67432?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67432, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-67432

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