CVE-2026-35021: CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in Anthropic Claude Code
Anthropic Claude Code CLI and Claude Agent SDK contain an OS command injection vulnerability in the prompt editor invocation utility that allows attackers to execute arbitrary commands by crafting malicious file paths. Attackers can inject shell metacharacters such as $() or backtick expressions into file paths that are interpolated into shell commands executed via execSync. Although the file path is wrapped in double quotes, POSIX shell semantics (POSIX §2.2.3) do not prevent command substitution within double quotes, allowing injected expressions to be evaluated and resulting in arbitrary command execution with the privileges of the user running the CLI.
AI Analysis
Technical Summary
CVE-2026-35021 is an OS command injection vulnerability in Anthropic Claude Code CLI and Claude Agent SDK. The issue occurs in the prompt editor invocation utility, where file paths containing shell metacharacters such as $() or backticks are interpolated into shell commands executed via execSync. Despite the file path being wrapped in double quotes, POSIX shell rules allow command substitution within double quotes, enabling arbitrary command execution with the user's privileges. This vulnerability is classified under CWE-78 and has a CVSS 4.0 score of 8.4, indicating high severity. The vulnerability affects version 0 of the product, and no patch or official remediation level has been published yet.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary OS commands with the privileges of the user running the Anthropic Claude Code CLI or Agent SDK. This can lead to unauthorized system access, data compromise, or further system manipulation. The vulnerability is rated high severity due to the potential for significant impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, avoid using untrusted input for file paths in the prompt editor invocation utility. Restrict CLI usage to trusted users and environments to minimize risk. Monitor vendor channels for updates and apply patches promptly once available.
CVE-2026-35021: CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in Anthropic Claude Code
Description
Anthropic Claude Code CLI and Claude Agent SDK contain an OS command injection vulnerability in the prompt editor invocation utility that allows attackers to execute arbitrary commands by crafting malicious file paths. Attackers can inject shell metacharacters such as $() or backtick expressions into file paths that are interpolated into shell commands executed via execSync. Although the file path is wrapped in double quotes, POSIX shell semantics (POSIX §2.2.3) do not prevent command substitution within double quotes, allowing injected expressions to be evaluated and resulting in arbitrary command execution with the privileges of the user running the CLI.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-35021 is an OS command injection vulnerability in Anthropic Claude Code CLI and Claude Agent SDK. The issue occurs in the prompt editor invocation utility, where file paths containing shell metacharacters such as $() or backticks are interpolated into shell commands executed via execSync. Despite the file path being wrapped in double quotes, POSIX shell rules allow command substitution within double quotes, enabling arbitrary command execution with the user's privileges. This vulnerability is classified under CWE-78 and has a CVSS 4.0 score of 8.4, indicating high severity. The vulnerability affects version 0 of the product, and no patch or official remediation level has been published yet.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary OS commands with the privileges of the user running the Anthropic Claude Code CLI or Agent SDK. This can lead to unauthorized system access, data compromise, or further system manipulation. The vulnerability is rated high severity due to the potential for significant impact on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, avoid using untrusted input for file paths in the prompt editor invocation utility. Restrict CLI usage to trusted users and environments to minimize risk. Monitor vendor channels for updates and apply patches promptly once available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-03-31T20:40:15.618Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d409d70a160ebd92d5a933
Added to database: 4/6/2026, 7:30:31 PM
Last enriched: 4/6/2026, 7:46:06 PM
Last updated: 4/7/2026, 5:42:24 AM
Views: 15
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