CVE-2026-96620

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.

CVSS

No CVSS.

References

Link	Resource
https://github.com/anthropics/claude-agent-sdk-python/commit/347a1cb88d7652199399db1b7f914e0a459a6662
https://github.com/anthropics/claude-agent-sdk-python/pull/1123
https://github.com/anthropics/claude-agent-sdk-python/releases/tag/v0.2.121
https://github.com/anthropics/claude-agent-sdk-python/security/advisories/GHSA-h4mw-j7qp-8mwm

Configurations

No configuration.

History

16 Oct 2026, 20:18

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-16 20:18

Updated : 2026-10-21 22:16

NVD link : CVE-2026-96620

Mitre link : CVE-2026-96620

CVE.ORG link : CVE-2026-96620

JSON object : View

Products Affected

No product.

CWE

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')

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