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Critical

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

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-96620

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-96620

claude-agent-sdk-python

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "vendor": "anthropics",
    "product": "claude-agent-sdk-python",
    "versions": [
      {
        "status": "affected",
        "version": "< 0.2.121"
      }
    ]
  }
]
Related CVEs
CVE-2026-96620

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#49990 · Revision 1
Added to Heist Feed
Publisher date
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