CVE-2026-96620

Claude Agent SDK: Argument Injection via resume Option Allows Arbitrary Command Execution

Published Oct 16, 2026 CVSS 4.0 · 9.2 Critical EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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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
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

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

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Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 21, 2026, 9:28 PM
Reserved
Sep 23, 2026, 2:35 PM
Status
Awaiting Analysis
Published
Oct 16, 2026, 8:18 PM
Modified
Oct 21, 2026, 10:16 PM