CVE-2026-54591
Description
A flaw was found in AsyncSSH, a Python package for SSHv2 protocol implementation. A malicious SSH server could exploit this vulnerability by sending specially crafted filenames containing directory traversal sequences to an AsyncSSH SCP client. This could allow the server to write arbitrary files to the client's filesystem, leading to unauthorized data modification or system disruption.
Statement
This Important flaw in AsyncSSH's SCP client allows a malicious SSH server to perform arbitrary file writes on the client's filesystem through directory traversal. This occurs when an AsyncSSH SCP client connects to a compromised or malicious server, enabling unauthorized data modification or system disruption on the client.
Mitigation
The core risk of this flaw is that the malicious server uses a path traversal trick to write files where it shouldn't on your client (like overwriting /etc/shadow or critical system binaries). By making the container's root filesystem read-only, you completely neutralize this attack. Even if the vulnerability is triggered, the container's kernel will block the unauthorized write attempt.
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Integrity
Technical Impact: Modify Files or Directories
The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Confidentiality
Technical Impact: Read Files or Directories
The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.
Frequently Asked Questions
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