Radicle discloses two critical flaws in its network protocol

Radicle, the peer-to-peer code collaboration stack built on Git, has disclosed two critical vulnerabilities in the network protocol its nodes use. All versions released so far are affected, and the project advises against using private repositories over the network until a fixed version ships.

Two flaws in the node transport

Both issues are in the node transport layer, not the repository data model. The first is a confidentiality failure: traffic between nodes is sent in plain text, so anyone watching the network path between two nodes can read the objects they exchange. Signed References still detect tampering in transit, but the encryption the protocol was expected to provide is missing — which matters above all for private repositories.

The second flaw is broken peer authentication in the connection handshake, which allows impersonation: an attacker can connect to a node and present a Node ID that is not its own. Private repositories are shared only with allow-listed Node IDs, so faking one lets an attacker fetch a private repository directly, without being on the network path.

How the flaws combine

Together the flaws are far more dangerous — an attacker on the path sees the Node IDs at both ends of a connection, reads whatever is exchanged, and can then use one of them to fetch the whole repository on demand. No setting or allow-list protects against someone on the path between your node and the node it syncs with. The cleartext issue was reported by Konstantinos Maninakis on 2026-06-24; the handshake flaw by cryptocode on 2026-08-12.

What users should do

Radicle recommends pausing private repositories over the network and stopping seeding them: list them with rad ls --private --all and block each one with rad block <RID>. The project prefers rad block over rad unseed, which falls back to the node's default policy — possibly allow. rad node stop shuts the node down entirely.

Radicle warns that every private repository ever transmitted to another node should be treated as leaked, and any unencrypted credentials, keys or tokens rotated. Tor and I2P are not sufficient: they hide traffic from an attacker on the path but do not prevent peer impersonation.

Fix will be a breaking release

With no version negotiation and a fix incompatible on the wire, a backward-compatible mitigation is not feasible: the release will break compatibility and bump the major version, splitting the network into upgraded and non-upgraded clusters. Radicle is replacing its Noise-based protocol with iroh, an open source peer-to-peer stack built on open standards that also brings NAT traversal, while keeping the storage layout compatible.