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TI-2026-69464 Aliases CVE-2026-88257GHSA-pgrr-g28j-jvp6

beam_mcp: nested tool argument constraints advertised but not enforced

Priority LOW 24CWE-20Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

ScriptKittyOS beam_mcp from 0.1.0 before 0.10.1 has improper input validation (CWE-20) in BeamMCP.Schema. The validate/2 function checks only the top-level arguments object, so constraints on nested objects and array items that the server advertises through tools/list are never enforced. An MCP client can send tool arguments that violate the advertised schema, such as an out-of-range number or an undeclared key inside a nested object. The impact depends on how the host's dispatch code handles such values.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

Improper Input Validation vulnerability in BeamMCP.Schema in ScriptKittyOS beam_mcp allows an MCP client to reach a tool's dispatch function with arguments that violate the input schema the server advertised. BeamMCP.Schema.validate/2 checked type, required, additionalProperties, enum and numeric bounds on the top-level arguments object only. Constraints inside nested objects and on array items (items, minItems, maxItems, minLength, maxLength, pattern, nested required, enum and additionalProperties: false) were advertised by tools/list and never checked at tools/call or prompts/get, and keywords outside the enforced subset (oneOf, anyOf, $ref) were advertised and ignored. A host whose dispatch code relies on the schema it declared receives values the schema forbids, such as an out-of-range number or an undeclared key inside a nested object. What the host does with such a value decides the impact. This issue affects beam_mcp: from 0.1.0 before 0.10.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00268 19th percentileScored 2026-11-07
Fix Fixed beam_mcp (ScriptKittyOS): 0.10.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ScriptKittyOSbeam_mcp0.1.0 to before 0.10.10.10.1Patch availableCNA
  • beam_mcp VendorScriptKittyOS Affected 0.1.0 to before 0.10.1 Fixed in 0.10.1 Patch available CNA

CPE names CNA · 1

CPEVersionsRoleVendor
cpe:2.3:a:scriptkittyos:beam_mcp:*:*:*:*:*:*:*:*——ScriptKittyOS
  • cpe:2.3:a:scriptkittyos:beam_mcp:*:*:*:*:*:*:*:* Versions — — ·ScriptKittyOS

Remediation

Upgrade ScriptKittyOS beam_mcp to version 0.10.1, which is the fixed version. The sources list no fixed version for any other product.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA beam_mcp (ScriptKittyOS) Fixed in 0.10.1

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    ScriptKittyOS beam_mcp 0.10.1, 289dbdbad641943b29a3b8d1eb36506cc8cec10a

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2026-69499 JSON boolean and null tool arguments reach dispatch as strings in beam_mcpPriority LOW 12
    Show all 2 records →

Timeline

  1. 2026-10-08 Threatist record created from CVE-2026-88257
  2. 2026-10-08 Alias added: GHSA-pgrr-g28j-jvp6

References

Patch 1

Advisory 1

Other 3

  • TI-2026-69499 JSON boolean and null tool arguments reach dispatch as strings in beam_mcp CVSS 4.0LOW 2.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences