CVE-2026-96620: Claude Agent SDK argument injection via resume option (< 0.2.121)
- Product
- claude-agent-sdk (PyPI)
- CVE
- CVE-2026-96620
- Affected
- < 0.2.121
- Fixed in
- 0.2.121
Last verified against sources: October 16, 2026
Am I affected?
claude-agent-sdk (PyPI): affected < 0.2.121. Fixed in 0.2.121.
What to do now
- Update claude-agent-sdk to 0.2.121 or later and do not pass untrusted input as the session ID to resume. [1]
General practice, not from the source: if the affected software could read tokens or credentials, rotate them after upgrading; pin versions and review changes before updating tools your agents run.
What happened
- According to GitHub Advisory Database's advisory (Oct 16, 2026), the Claude Agent SDK for Python passed the resume option to the Claude CLI without validation, allowing a value beginning with a dash to be interpreted as a CLI flag. [1]
Impact
- An attacker controlling the resume value could inject an --mcp-config flag defining a stdio MCP server, leading to arbitrary command execution at CLI startup. [1]
What was done
- Fixed in claude-agent-sdk 0.2.121. [1]
Sources
- GHSA-h4mw-j7qp-8mwm — GitHub Advisory Database
Every statement above was checked against these sources before publishing. Spotted an error? Tell us and we will correct it with a dated note.
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[CVE-2026-96620] CVE-2026-96620: Claude Agent SDK argument injection via resume option (< 0.2.121)
Product: claude-agent-sdk (PyPI) | Affected: < 0.2.121 | Fixed in: 0.2.121
Summary: According to GitHub Advisory Database's advisory (Oct 16, 2026), the Claude Agent SDK for Python passed the resume option to the Claude CLI without validation, allowing a value beginning with a dash to be interpreted as a CLI flag.
Source & remediation on AgentArmorHQ: https://agentarmorhq.com/incidents/2026/10/cve-2026-96620-claude-agent-sdk-resume-injectionCorrections
Report an error or request a correction. We review requests within 5 business days and add a dated correction note.
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