Transmission
Transmission downloads and shares files with other people using BitTorrent. It’s made by Transmission Project.
Criminals have used its name in fake downloads or scams, so get it only from transmissionbt.com.
What it is
Transmission uses torrent files and magnet links to download files from other people. It also uploads pieces to others and can keep sharing after a download finishes.
It reads the torrent files you open and reads and writes the files being downloaded or shared. You can also choose a folder for it to watch for new torrent files.
Transmission is a legitimate open-source app. Its developers say it contains no bundled advertising and does not track users. The official Mac download is version 4.1.4, which fixes a security flaw.
Who makes it
A volunteer project that develops the open-source Transmission BitTorrent client. Its website is transmissionbt.com.
Is it the real one?
Every Mac app carries a signature from the developer who made it. Apple checks who the developer is before handing out the certificate, and macOS refuses to open an app whose signature has been tampered with.
HARD hasn’t yet recorded the signature on a real copy of Transmission. Its Mac app shows who signed the copy you have.
Its bundle ID, the name macOS knows it by, is org.m0k.transmission. Download it only from transmissionbt.com, not from an ad or a link someone sends you.
Fakes. In March 2016, attackers distributed altered Transmission installers containing KeRanger ransomware through the official website. In August 2016, an altered download there carried Keydnap, which stole keychain data and installed a backdoor; the project removed the malicious downloads.
What it connects to
In normal use, Transmission talks to these places on the internet. A firewall that asks before apps connect, like the one in HARD’s Mac app, will show them.
| Address | Why |
|---|---|
update.transmissionbt.com | Checks for app updates. |
dht.transmissionbt.com | Helps find other people sharing a torrent. |
portcheck.transmissionbt.com | Checks whether incoming connections can reach the app. |
Security record
Problems with Transmission or Transmission Project in the last three years, newest first. Keeping the app up to date covers the ones that were fixed.
| When | What happened | Source |
|---|---|---|
| A Mac flaw could allow code execution if an attacker already had local write access to the user's preferences; version 4.1.4 fixed it. | ↗ | |
| A flaw could let malicious webpages control Transmission when remote access was enabled; version 4.1.3 fixed it. | ↗ | |
| The web interface could be embedded in another webpage to trick users into clicking its controls; version 4.1.2 fixed it. | ↗ |
References
- Transmission official website transmissionbt.com
- Transmission downloads transmissionbt.com
- Transmission macOS bundle identifier in build settings raw.githubusercontent.com
- Transmission Help: Getting Started raw.githubusercontent.com
- Transmission Help: Managing your transfers raw.githubusercontent.com
- Transmission Mac update settings raw.githubusercontent.com
- Transmission peer discovery source raw.githubusercontent.com
- Transmission port-check source raw.githubusercontent.com
- Transmission releases github.com
- Transmission 4.1.4 release notes github.com
- Transmission remote-control security fix github.com
- Transmission 4.1.3 release notes github.com
- Transmission clickjacking report github.com
- Debian security tracker: CVE-2026-38978 security-tracker.debian.org
- Palo Alto Networks: KeRanger in Transmission installers unit42.paloaltonetworks.com
- ESET: Keydnap distributed through an altered Transmission app welivesecurity.com