fix(cli): confine attachment downloads to --dir, sanitize mail filename (P1 path traversal)

[bhekanik]

Problem (P1 security — arbitrary file write)

mxr attachments download <id> --dir <dir> did target_dir.join(&attachment.filename) with the raw, mail-controlled filename. Path::join discards the base on an absolute component and ../ walks upward, so a hostile filename (/etc/crontab, ../../../.ssh/authorized_keys) writes outside --dir — arbitrary-file-overwrite / code-exec. The daemon side already sanitizes; this CLI convenience copy did not.

Fix

New safe_download_name reduces the filename to its final path component (Path::file_name()), falling back to a stable attachment-<id> for .././empty/non-UTF-8. target_dir.join(name) is then always a direct child. Normal filenames unchanged. Tests cover ../../evil, /etc/evil, .., `` (all confined) and report.pdf (preserved).

CI note: workspace clippy is red on pre-existing 1.97 lints until #111 (CI-unblock) merges; will rebase.

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Summary by cubic

Sanitizes attachment filenames and confines downloads to the chosen --dir, preventing path traversal and arbitrary file writes. Normal filenames remain unchanged.

• Bug Fixes
  • Added safe_download_name to keep only the final path component; falls back to attachment-<id> for .., ., empty, or non-UTF-8 names.
  • --dir downloads now always write directly under the chosen directory; tests cover ../../evil, /etc/evil, .., empty, and report.pdf.

^{Written for commit 94a8377. Summary will update on new commits.}

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Project	Deployment	Actions	Updated (UTC)
mxr-mail	Ready	Preview, Comment	Jul 11, 2026 2:10am

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Configuration used: defaults

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📥 Commits

Reviewing files that changed from the base of the PR and between c9b2f59 and 94a8377.

📒 Files selected for processing (1)

• crates/daemon/src/commands/mutations/attachments.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/cli-attachment-path-traversal

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[cubic-dev-ai]

No issues found across 1 file

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