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Argument Injection in SSHFS bracketed mount source handling
CVE-2026-48711 is a high-severity argument injection vulnerability in SSHFS affecting versions 1.4 through 3.7.5. SSHFS accepts bracketed mount sources intended to represent host components, and during processing, find_base_path() strips the surrounding brackets as though the value were an IPv6 literal. If the resulting normalized host begins with a hyphen, SSHFS passes that value directly to the ssh client without validating that it is a legitimate hostname. This allows a crafted mount source to be reinterpreted by ssh as a command-line option rather than a destination host. Under the documented exploitation condition where the caller also supplies a path-valued sftp_server, ssh treats the attacker-controlled normalized host as an option and the server path as the destination argument. An injected ProxyCommand can then be executed locally before any SSH connection establishment or authentication succeeds.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation results in arbitrary local command execution in the security context of the user running SSHFS. Because execution occurs before SSH authentication completes, the vulnerability can be abused without valid SSH credentials to the target server. The primary consequence is compromise of the invoking user account, which may enable local persistence, access to that user's data, execution of follow-on tooling, and abuse of any privileges or trust relationships available to that account.
If you can’t patch tonight, do this now.
Until patched, avoid passing attacker-controlled or untrusted mount source strings to SSHFS, including through wrappers, automation, desktop integrations, or helper scripts. Review and restrict any configuration that supplies a path-valued sftp_server in combination with externally influenced mount sources, since that condition is required for the documented exploit path. Where possible, constrain who can invoke SSHFS and validate mount source syntax before handing it to the client.
Patch, then assume compromise.
Upgrade SSHFS to version 3.7.6 or later. The fix rejects normalized hostnames that begin with a hyphen after bracket processing and adds an ssh end-of-options marker before the hostname so attacker-controlled input cannot be interpreted as ssh command-line options.
No public exploits tracked yet. Mallory keeps watching.
4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.