Description
Claude Agent SDK is a Python SDK for Claude Code. Prior to 0.2.121, the resume option is passed to the Claude CLI as a separate token without validation, so a dash-leading value is parsed as an independent CLI flag. An attacker can inject the --mcp-config flag to define a stdio MCP server, causing arbitrary command execution at CLI startup outside the SDK permission controls. The issue is exploitable when an application passes untrusted input as the session ID to resume. This issue is fixed in version 0.2.121.
Published: 2026-10-16
Score: 9.2 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-h4mw-j7qp-8mwm Claude Agent SDK: Argument Injection via resume Option Allows Arbitrary Command Execution
History

Fri, 16 Oct 2026 20:00:00 +0000

Type Values Removed Values Added
Description Claude Agent SDK is a Python SDK for Claude Code. Prior to 0.2.121, the resume option is passed to the Claude CLI as a separate token without validation, so a dash-leading value is parsed as an independent CLI flag. An attacker can inject the --mcp-config flag to define a stdio MCP server, causing arbitrary command execution at CLI startup outside the SDK permission controls. The issue is exploitable when an application passes untrusted input as the session ID to resume. This issue is fixed in version 0.2.121.
Title Claude Agent SDK: Argument Injection via resume Option Allows Arbitrary Command Execution
Weaknesses CWE-20
CWE-78
CWE-88
References
Metrics cvssV4_0

{'score': 9.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-16T19:44:01.260Z

Reserved: 2026-09-23T14:35:50.128Z

Link: CVE-2026-96620

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-16T20:18:28.293

Modified: 2026-10-16T20:18:28.293

Link: CVE-2026-96620

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-20

    Improper Input Validation

  • CWE-78

    Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

  • CWE-88

    Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')