Listen to this Post
The vulnerability stems from improper neutralization of special elements used in shell commands within the Claude Code environment. Specifically, errors in parsing logic related to the Internal Field Separator ($IFS) environment variable and short-form command-line flags (e.g., -a, -l) allowed for argument injection. The read-only validation mechanism, designed to sanitize user input before passing it to a shell interpreter, incorrectly tokenized commands containing these elements. An attacker could craft a malicious string where `$IFS` is used to glitch the parser, separating what the validator saw as a single, safe argument into multiple, harmful ones at execution time. Similarly, by embedding short flags within a seemingly benign argument, an attacker could subvert the validation checks. When this manipulated input was processed by the underlying system shell, it bypassed the intended security controls, allowing the execution of arbitrary system commands with the privileges of the Claude Code process.
DailyCVE Form
Platform: Claude Code
Version: Not specified
Vulnerability: Command Validation Bypass
Severity: Critical
Date: 2025-12-03
Prediction: Patch Deployed
What Undercode Say:
Analytics:
Example leveraging IFS for argument injection VALIDATED_INPUT="safe_command" MALICIOUS_INPUT="safe_command$IFS&&$IFSrm$IFS-rf$IFS/" Example using short flag injection Validator sees "-allowed_flag", but execution parses as "-a -l -l ..." INJECTED_FLAGS="-allowed_flag"
How Exploit:
- Attacker supplies crafted input with `$IFS` or short flags.
2. Input passes Claude Code’s read-only validation.
3. Shell interpreter parses the special syntax.
4. Injected commands execute on the host.
Protection from this CVE:
Update to latest version. Implement strict command allow-listing. Use parameterized APIs.
Impact:
Arbitrary Code Execution. System Compromise.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
