The Week of Sandbox Escapes Day 5: GitPwned: Allowlist to RCE

**Codex CLI sandbox escape via git show --output** — The report details an exploit in Codex CLI where the safe-command allowlist permits git show to run unsandboxed; by abusing git show --output and --format an attacker can write arbitrary content to .git/config (for example setting diff.external to a malicious command), leading to remote code execution when git diff is later invoked. The issue bypasses the sandbox and approval flow, was reported in January 2026, assigned CVSS 8.6, and patched in v0.95.0; recommended mitigations include blocking dangerous flags, removing git from the allowlist, or overriding diff.external at runtime.