Cwtch is a communication application (and associated libraries) that uses Tor v3 Onion Services to establish surveillance resistant channels between people. Cwtch has been designed to be secure, private, and resilient.
Cwtch 1.17.2 is now available for download!
This update contains fixes for several security issues and we recommend updating Cwtch right away. There are also stability improvements related to the new Hybrid Groups experiment released in Cwtch 1.17!
In This Release
- Fixed several security issues; thanks to Eduardo Camarillo for reporting these!
- Incoming contact requests were incorrectly given ExchangeAttributes permission before being accepted. (Versions Impacted: 1.16 - 1.17.1. Note: The “Block Unknown Contacts” setting would mitigate this issue, but it is not enabled by default.)
- Manually importing a maliciously-crafted server invitation could result in a nil pointer exception**, resulting in the termination of the Cwtch process. (Versions Impacted: 1.1 - 1.17.1)
- Connecting to a malicious server with the Legacy Groups experiment enabled could result in a nil pointer exception, resulting in the termination of the Cwtch process. (Versions Impacted: 1.1 - 1.17.1. Requires: Group Experiment Enabled)
- Accepting a malicious file download with the File Downloads experiment enabled could cause an out-of-memory error, resulting in the termination of the Cwtch process. (Versions Impacted: 1.2 - 1.17.1. Requires: File Sharing Experiment Enabled; in addition to a file share from a trusted contact. If the Image Preview Experiment was also enabled then this attack requires no user interaction, otherwise the attack requires a user to accept the malicious file download.)
- Users with the Invite permission in an experimental Hybrid Group could issue a malformed invite resulting in the demotion of another member to “user” level. The issue does not allow the attacker to increase privileges. (Versions Impacted: 1.17.1. Requires: A malicious hybrid group member with either invite permissions, or a group with the “anyone can invite (+i)” flag set.)
- A number of other code-quality issues that did not have security impacts.
- Bug Fixes / Improvements:
- Fixed a bug with Appear Offline not working on Android
- Combined the "appear offline at startup" profile setting and the temporary "appear offline" status setting. Having these be different was confusing, and did not work correctly on Android devices that quietly kill and restart the application frequently.
- Added Reconnect buttons for profiles and conversations
- Fixed a bug where Hybrid Groups with large member counts could stop syncing the member list. We believe Hybrid Groups should support around 64 members now, and we will work on increasing this number in the future.
- Added ability to click profile pictures in hybrid groups to add them as a contact or copy their cwtch address
- Fixed a bug with profile names/pictures syncing slowly
- Tidied up Add Contact to Group dropdown in hybrid groups
- Connection stability improvements: Cwtch should now be better at detecting when a tor circuit has stopped working and marking the associated contact as offline. This feeds in to Cwtch’s reconnection-attempt logic, which should improve connectivity overall.
- Update tor to 0.4.9.13
Calling all translators!
We absolutely love our amazing volunteer translators who have helped translate Cwtch into 24 different languages!
Unfortunately, the timing of Cwtch 1.17 coincided with the end of open-source support from our old translation platform, which is going AI-first. We value the human touch on our translations as much as our code, and so have decided to move to a self-hosted translation platform. If you've done translations for Cwtch before or want to get started, please reach out and we'll send you an invite to the new system!
Cwtch remains fully translated in 24 languages everywhere except the new Hybrid Groups features, and we hope to cut a follow-up release soon getting us back up to 100% translated.
Download Cwtch 1.17.2
You can download Cwtch from https://cwtch.im/download.
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A special thanks to the amazing volunteer translators and testers who made this release possible.
Reproducible Bindings
Cwtch 1.17 is based on libCwtch version libCwtch-autobindings-2026-08-31-12-36-v0.3.0.
The repliqate scripts to reproduce our build environment can be found here: https://git.openprivacy.ca/sarah/repliqate-runner
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