Security readout for executives and security teams
Plain-English summary
CVE-2026-30618 is a critical remote code execution issue in xszyou Fay 4.3.1. If its MCP management interface is publicly reachable, an unauthenticated attacker may configure attacker-controlled command execution through MCP STDIO server handling. Successful exploitation can run commands as the Fay service.
Executive priority
Treat as urgent for any Fay 4.3.1 deployment with exposed management access. The impact is full server compromise in the Fay service context, but public evidence does not confirm active exploitation or a named patch.
Technical view
The source bundle describes CWE-94 in Fay 4.3.1 MCP STDIO server management and command execution handling. CVSS 3.1 is 9.8: network-accessible, low complexity, no privileges, no user interaction, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely where Fay 4.3.1 is deployed and the MCP management interface is reachable from untrusted networks. The CVE record provides no CPEs, and the affected vendor/product fields are listed as n/a, so inventory confirmation is required.
Exploitation context
The bundle says remote attackers can abuse a publicly exposed MCP management interface to configure MCP STDIO servers with attacker-controlled commands. CISA KEV is false in the bundle, and no cited source confirms active exploitation.
Researcher notes
Evidence is limited to the CVE description, CVSS, OX advisory reference, and upstream repository. The record lacks CPEs and named fixed versions. Validate exposure through configuration and network reachability without attempting command execution.
Mitigation direction
- Remove public access to the MCP management interface.
- Restrict management access to trusted networks or authenticated administrative paths.
- Disable MCP STDIO server management where it is not operationally required.
- Run the Fay service with least-privilege permissions.
- Check upstream Fay and OX guidance for patches or configuration changes.
- Monitor for unexpected MCP configuration changes and child process activity.
Validation and detection
- Inventory systems running xszyou Fay 4.3.1.
- Confirm whether any MCP management interface is internet-accessible.
- Review Fay configuration for unexpected MCP STDIO server definitions.
- Check logs for unauthorized management changes or unusual process execution.
- Verify service account privileges limit command impact.
- Track vendor repository and advisory updates for remediation status.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-30618 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem/CVE reference, mitre
- https://github.com/xszyou/FayCVE reference, mitre
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.