Affected: magic-wormhole

Magic Wormhole makes it possible to get arbitrary-sized files and directories from one computer to another. From 0.21.0 to before 0.23.0, receiving a file (wormhole receive) from a malicious party could result in overwriting critical local files, including ~/.ssh/authorized_keys and .bashrc. This could be used to compromise the receiver's computer. Only the sender of the file (the party who runs wormhole send) can mount the attack. Other parties (including the transit/relay servers) are excluded by the wormhole protocol. This vulnerability is fixed in 0.23.0.

Affected: PyPI: magic-wormhole

### Impact _What kind of vulnerability is it? Who is impacted?_

Receiving a file (`wormhole receive`) from a malicious party could result in overwriting critical local files, including `~/.ssh/authorized_keys` and `.bashrc`. This could be used to compromise the receiver's computer.

Only the sender of the file (the party who runs `wormhole send`) can mount the attack. Other parties (including the transit/relay servers) are excluded by the wormhole protocol.

### Patches _Has the problem been patched? What versions should users upgrade to?_

The bug has been fixed in magic-wormhole 0.23.0. All users should upgrade to this version.

The vulnerability first surfaced in the 0.21.0 release on 23-Oct-2025.

### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_

As a workaround, the receiver can override the sender's filename with the `--output` or `-o` option. For example: `wormhole receive -o shopping-list.txt` will write the file to `shopping-list.txt` in the local directory, regardless of what the sender tries to do. To be effective, this option must be added to every invocation of `wormhole receive` / `wormhole rx`.

### References _Are there any links users can visit to find out more?_

Incoming file transfer requests include a `filename`, used to decide where the file contents will be written. Well-behaving senders compute this from the `basename()` of the sent file (which discards all but the last segment of the path). To guard…

Affected: PyPI: magic-wormhole

### Impact _What kind of vulnerability is it? Who is impacted?_

Receiving a file (`wormhole receive`) from a malicious party could result in overwriting critical local files, including `~/.ssh/authorized_keys` and `.bashrc`. This could be used to compromise the receiver's computer.

Only the sender of the file (the party who runs `wormhole send`) can mount the attack. Other parties (including the transit/relay servers) are excluded by the wormhole protocol.

### Patches _Has the problem been patched? What versions should users upgrade to?_

The bug has been fixed in magic-wormhole 0.23.0. All users should upgrade to this version.

The vulnerability first surfaced in the 0.21.0 release on 23-Oct-2025.

### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_

As a workaround, the receiver can override the sender's filename with the `--output` or `-o` option. For example: `wormhole receive -o shopping-list.txt` will write the file to `shopping-list.txt` in the local directory, regardless of what the sender tries to do. To be effective, this option must be added to every invocation of `wormhole receive` / `wormhole rx`.

### References _Are there any links users can visit to find out more?_

Incoming file transfer requests include a `filename`, used to decide where the file contents will be written. Well-behaving senders compute this from the `basename()` of the sent file (which discards all but the last segment of the path). To guard…