CVE-2026-67531

CRITICALPre-NVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 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
Elevated
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.3Exploit: Elevated riskExposed: 0

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

FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 1.5.7, the sandboxed codecall:execute tool exposes live host Zod schema instances to the script via getTool(), and because Zod v4 defines _zod as a non-configurable, non-writable own property, the ECMAScript Proxy invariants force the security membrane to hand back the raw host object, letting a script reach _zod.constr.constructor (the host Function constructor) and execute arbitrary code in the server process. A single tools/call is sufficient to escape the sandbox and achieve remote code execution as the server user, exposing everything the process holds such as OAuth client secrets, JWT_SECRET, session keys, database credentials, and cloud instance metadata. Because the framework's DEFAULT_AUTH_OPTIONS is public mode, an unconfigured server serves this to unauthenticated callers, and on authenticated servers an indirect prompt injection in tool output or fetched content can trigger it without a human attackerThis issue is fixed in version 1.5.7.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
73(Attend)
EG Risk 73/100SSVC: Attend

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
Severity93% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
36%
KEV
Not listed

Published

August 5, 2026

Last Modified

August 6, 2026

Advisory Details (2)

Auto-updated Aug 23, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

CodeCall sandbox escape to host RCE via live Zod schema exposed by getTool · Advisory · agentfront/frontmcp · GitHub

https://github.com/agentfront/frontmcp/security/advisories/GHSA-mp29-fxh8-92px
github_commit Patch Available

commit 209cddd19a8d (agentfront/frontmcp)

Patch available: agentfront/frontmcp v1.5.7 (contains commit 209cddd19a8d)

https://github.com/agentfront/frontmcp/commit/209cddd19a8d4db0777f725b527818da7df6f67f

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 47× 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 04:38 UTCEG score recompute
  2. 2026-08-30 01:22 UTCEPSS rescore
  3. 2026-08-29 21:15 UTCEG score recompute
  4. 2026-08-28 21:42 UTCEPSS rescore
  5. 2026-08-27 15:19 UTCEG score recompute
  6. 2026-08-26 19:06 UTCEG score recompute
  7. 2026-08-26 14:47 UTCEPSS rescore
  8. 2026-08-25 16:05 UTCEG score recompute
  9. 2026-08-25 13:49 UTCEPSS rescore
  10. 2026-08-24 17:38 UTCEG score recompute
  11. 2026-08-24 10:11 UTCEG score recompute
  12. 2026-08-23 00:59 UTCEG score recompute
  13. 2026-08-23 00:19 UTCEPSS rescore
  14. 2026-08-22 02:58 UTCEG score recompute
  15. 2026-08-21 23:49 UTCEPSS rescore
  16. 2026-08-21 01:18 UTCEG score recompute
  17. 2026-08-20 22:56 UTCEPSS rescore
  18. 2026-08-19 18:51 UTCEG score recompute
  19. 2026-08-19 17:04 UTCEPSS rescore
  20. 2026-08-18 15:44 UTCEG score recompute
  21. 2026-08-18 13:48 UTCEPSS rescore
  22. 2026-08-17 14:57 UTCEG score recompute
  23. 2026-08-17 13:47 UTCEPSS rescore
  24. 2026-08-16 16:59 UTCEG score recompute
  25. 2026-08-16 14:56 UTCEPSS rescore
Show 22 more
  1. 2026-08-16 02:20 UTCEG score recompute
  2. 2026-08-15 04:21 UTCEG score recompute
  3. 2026-08-15 01:30 UTCEPSS rescore
  4. 2026-08-13 23:00 UTCEG score recompute
  5. 2026-08-13 22:00 UTCEPSS rescore
  6. 2026-08-12 14:02 UTCEG score recompute
  7. 2026-08-12 13:51 UTCEPSS rescore
  8. 2026-08-11 15:56 UTCEG score recompute
  9. 2026-08-11 01:17 UTCEG score recompute
  10. 2026-08-11 00:00 UTCEPSS rescore
  11. 2026-08-09 16:19 UTCEG score recompute
  12. 2026-08-09 13:47 UTCEPSS rescore
  13. 2026-08-08 18:22 UTCEG score recompute
  14. 2026-08-08 16:37 UTCEPSS rescore
  15. 2026-08-07 16:44 UTCEG score recompute
  16. 2026-08-07 02:04 UTCEG score recompute
  17. 2026-08-06 22:24 UTCEG score recompute
  18. 2026-08-06 14:58 UTCEG score recompute
  19. 2026-08-06 13:47 UTCEPSS rescore
  20. 2026-08-06 00:19 UTCEG score recompute
  21. 2026-08-05 23:20 UTCEG score recompute
  22. 2026-08-05 23:20 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-67531?
CVE-2026-67531 is a critical vulnerability published on August 5, 2026. FrontMCP is a TypeScript-first framework for the Model Context Protocol (MCP). Prior to 1.5.7, the sandboxed codecall:execute tool exposes live host Zod schema instances to the script via getTool(), and because Zod v4 defines zod as a non-configurable, non-writable own property, the ECMAScript…
When was CVE-2026-67531 disclosed?
CVE-2026-67531 was first published in the National Vulnerability Database on August 5, 2026, with the most recent update on August 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-67531 actively exploited?
CVE-2026-67531 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 63.9% of all scored CVEs.
What is the CVSS score of CVE-2026-67531?
CVE-2026-67531 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2026-67531?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-67531, 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.

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