CVE-2026-53689: libnfs through 6

Synopsis

An integer overflow vulnerability in libnfs through version 6.0.2 allows a crafted NFS server to trigger memory corruption during a client connection. The flaw is reachable over the network, requires no authentication, but does require the victim to initiate a connection to a malicious server. Successful exploitation gives an attacker the ability to read or modify sensitive data in the connecting process. A patched-image rebuild at commit 55c18ea is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The vulnerable code path is reached when the client connects to a remote NFS server, so the attacker must be able to present a reachable, crafted server over the network.

• AuthenticationNot required

  No credentials are needed; the overflow occurs during the initial connection handshake before any authentication exchange.

• Victim interactionRequired

  A user or process on the target host must initiate a connection to the attacker-controlled NFS server, making this a social-engineering or configuration-manipulation vector.

• Attack complexityDetail

  Exploitation is rated AC:H, meaning the attacker depends on environmental factors outside their direct control, such as memory layout or timing, to reliably trigger the overflow.

Blast Radius

• An attacker who triggers the overflow can read memory from the connecting process, exposing secrets, tokens, or file data held in that process.
• The same memory corruption can allow the attacker to overwrite in-process data structures, tampering with file content or application state in the connecting client.
• Availability impact is rated low, meaning the connecting process may crash or become unstable, though a full denial of service is not guaranteed.