GHSA-h4mw-j7qp-8mwm
Claude Agent SDK: Argument Injection via resume Option Allows Arbitrary Command Execution
At a glance
- Published
- Updated
- CVE
- CVE-2026-96620
- CVSS_V4
- 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
Description
The Claude Agent SDK for Python passed the `resume` option to the Claude CLI without validation, allowing a value beginning with `-` to be interpreted as a separate CLI flag. An attacker who controlled the `resume` value could inject an `--mcp-config` flag defining a stdio MCP server, resulting in arbitrary command execution at CLI startup that bypassed the SDK's permission controls. Exploitation required an application to pass untrusted input as the session ID to resume. Users are advised to update to the latest version of the claude-agent-sdk package. Thank you to hackerone.com/moamenmahmood for reporting this issue.
Affected packages
| Package | Versions |
|---|---|
| PyPI · claude-agent-sdk | introduced 0, fixed 0.2.121 |
References
- https://github.com/anthropics/claude-agent-sdk-python/security/advisories/GHSA-h4mw-j7qp-8mwm WEB
- https://github.com/anthropics/claude-agent-sdk-python/pull/1123 WEB
- https://github.com/anthropics/claude-agent-sdk-python/commit/347a1cb88d7652199399db1b7f914e0a459a6662 WEB
- https://github.com/anthropics/claude-agent-sdk-python PACKAGE
- https://github.com/anthropics/claude-agent-sdk-python/releases/tag/v0.2.121 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |