MacVNC is an experimental native Rust Windows client for Apple's High Performance Screen Sharing. Developed by AnchorSprint. Security fixes are accepted for the current development branch; older experimental builds do not have a separate maintenance commitment.

Use GitHub private vulnerability reporting when available. Do not put passwords, keys, saved profiles, private hostnames, desktop captures or exploitable vulnerability details in a public issue. If private reporting is unavailable, open a public issue requesting a private contact channel without disclosing the vulnerability. No response-time guarantee or independent security audit is claimed.

• Authentication is attempted only against the configured Mac. Rejected logins are never automatically retried. The default host is blank.
• Windows DPAPI encrypts remembered passwords for the current OS account. New saved secrets bind the host, port and username inside the protected payload; changing those visible fields invalidates password reuse and auto-connect.
• Older profiles retain the remembered password but require an explicit Connect after checking the destination. Saving upgrades them to the bound format.
• Profile writes replace the previous file atomically. Profile and legacy encryption-state reads have size limits. Password buffers are zeroized where owned; this does not guarantee removal of all copies from process memory, operating-system paging or crash dumps.
• Host and username remain visible in the local profile. DPAPI does not protect against malicious software already running as the same Windows user.
• Forget replaces the native profile with an empty record so legacy credentials are not imported again. Historical fixture files are left untouched.

• HP media packets are authenticated with SRTP and checked for replay before acceptance. Encrypted control traffic uses Apple's legacy AES-CBC protocol. Apple type-30 authentication does not provide modern server identity verification. Encryption is not a substitute for trusting the destination.
• Use a trusted network or a correctly configured private tunnel. Do not expose Screen Sharing directly to the public internet. HP needs its UDP media path as well as TCP; a TCP-only tunnel does not cover the full native session.
• Network lengths, packet queues and decoded image sizes are bounded. Malformed records fail closed. FFmpeg is C code accessed through an unsafe Rust ABI adapter; a memory-safe UI does not make the decoder memory-safe.
• FFmpeg is loaded from the application directory or the explicitly configured developer runtime directory. Keep executable and DLL directories trusted and retain replaceable DLLs and their license/source notices.
• The reverse-engineered protocol can change with macOS updates. Authentication, playback, input and recovery need separate live validation; passing offline tests does not establish interoperability or security on every Mac.
• Experimental file copying uses the existing successfully authenticated HP session. It never uses the authentication-bypass framing present in some public protocol research. Native file messages and reply buffers are bounded; data moves through separate bounded queues rather than the input queue. Local downloads use exclusive staging files and do not replace existing files. Uploads require explicit consent to possible replacement on the Mac. No native cancel, remote atomic replacement or partial-file cleanup guarantee has been established: stopping an in-flight transfer closes the session, and a partial remote file may remain. File transfer has not been live-validated on macOS.

The Windows updater checks public stable releases only from ossmalaysia/macvnc. It uses HTTPS with the OS trust roots, restricts redirects to GitHub release hosts and requires the release SHA-256 checksum, matching version/platform metadata and a Windows x64 executable. Archive sizes, paths and file inventories are bounded; traversal, device names, links and unexpected runtime entries are rejected. Installation uses a same-volume staging directory, waits for the old process to exit and keeps backups until the restarted UI acknowledges startup. No account credentials are sent to the update service. These releases are unsigned: the checksum detects corruption but does not add publisher authentication beyond HTTPS and trust in the GitHub release account. Install into a folder writable only by trusted local users. The updater does not elevate privileges. If rollback cannot complete, backups remain available for recovery; the updater reports the failure instead of discarding them.

There is no automatic upload of diagnostics. Opt-in MACVNC_DIAGNOSTICS_PATH writes local aggregate timing and decoder counters; do not attach saved profiles, raw traffic or private screen contents to issues. Review logs before sharing. The developer website opens only when its link is clicked.

Rust and Node dependency versions are recorded in lockfiles. Use cargo audit and npm audit for current advisory results; a clean scan only covers known advisories in the scanned dependency set. FFmpeg and its bundled native libraries require separate upstream review. There is no claim that all dependencies have been independently audited.

Published binaries must include matching licenses and corresponding source materials described in THIRD_PARTY.md. Builds are unsigned unless a release explicitly states otherwise. A checksum detects changed bytes but does not by itself establish publisher identity or a reproducible build.

The supported application is the native Rust client. The protocol fixture tree is used only for offline regression coverage and is not packaged for users.

Checks performed against the current main branch:

• cargo audit: completed successfully with two low-risk maintenance warnings, paste 1.0.15 (RUSTSEC-2024-0436) and ttf-parser 0.25.1 (RUSTSEC-2026-0192). Neither advisory reports a known exploitable vulnerability; both are unmaintained transitive dependencies. They cannot be removed safely without changing the current GUI/font dependency tree, so they remain tracked for a future dependency update.
• npm audit --omit=dev: no production vulnerabilities reported. Node files are build and source-hygiene utilities, not part of the shipped client.
• Repository secret scan: no credentials, private keys or tokens found. Synthetic password strings in profile unit tests are test fixtures only (low, accepted).
• Workflow review: CI and release workflows use read-only defaults, pinned action SHAs, disabled checkout credentials, separate write-scoped publishing, and a protected release environment. No pull_request_target workflow was found.
• Rust workspace tests and Clippy pass with warnings denied.

High: none found in this review.

Medium: Apple Screen Sharing type-30 authentication and the legacy AES-CBC control channel do not provide modern server identity verification. The client must continue to require a trusted destination/network; replacing this requires compatibility with Apple's protocol and cannot be fixed locally without breaking interoperability.

Low: FFmpeg is native C code reached through an unsafe Rust ABI boundary; upstream decoder vulnerabilities remain possible. Keep DLL loading directories trusted and update the bundled FFmpeg release. The two unmaintained Rust crates listed above are also tracked as low-risk maintenance debt.

This review is a point-in-time engineering check, not an independent security audit or a guarantee that future dependencies, releases or protocol peers are safe.