Radicle: Disclosure of Vulnerability in the Network Protocol

Radicle’s peer-to-peer network protocol contains two critical flaws that expose confidential data and allow impersonation. Network traffic between nodes is sent in cleartext, so anyone able to observe the path can read exchanged objects; repository integrity remains protected by Signed References, so modification is detectable, but confidentiality of private repositories is lost. Peer authentication in the handshake is also broken: an attacker can present a Node ID that is not their own and, if that Node ID is allow-listed, fetch private repositories. The impersonation flaw is harder to exploit alone because an attacker must know an allow-listed Node ID, but combined with an on-path eavesdropper - who can both read traffic and learn Node IDs - the attacker can both observe syncs and later fetch entire repositories. Both issues affect every released Radicle version; the first was reported by Konstantinos Maninakis (2026-06-24) and the second by cryptocode (2026-08-12).

Immediate mitigation is to stop using and stop seeding private repositories until a breaking, incompatible network fix is released. Users should assume any private repo ever transmitted over the network has been leaked and rotate any exposed credentials, keys, or tokens. Commands to block seeding (rad ls private all; rad block; rad node stop) are provided; note blocking does not delete local storage or undo past exposure and peers that already fetched data remain a risk. The planned remediation replaces the custom transport with iroh, a standards-based peer-to-peer stack; that change will be backwards-incompatible, cause a major version bump and temporary network partition while migration is completed. Acknowledgements were given to the reporters.