CVE-2025-20668: Critical Out of Bounds Write in scp leading to Privilege Escalation

Overview

In a world where cybersecurity has become a significant concern for individuals and businesses alike, keeping track of vulnerabilities and assessing their potential impact is of paramount importance. One such vulnerability recently identified is CVE-2025-20668, a critical flaw in the Secure Copy Protocol (scp), which could potentially lead to local privilege escalation. This vulnerability affects all users of scp, a widely used method of securely transferring files between a local and a remote host. The severity of this flaw cannot be overstated, given the potential consequences if exploited.

Vulnerability Summary

CVE ID: CVE-2025-20668
Severity: Critical, CVSS score of 7.8
Attack Vector: Local
Privileges Required: System
User Interaction: None
Impact: Potential system compromise or data leakage

Affected Products

Product | Affected Versions

scp | All versions prior to patch ALPS09625562

How the Exploit Works

The exploit works by taking advantage of an out of bounds write vulnerability due to a missing bounds check within the scp implementation. An attacker, who has already obtained the System privilege, can use this flaw to write data beyond the allocated memory area. This could potentially overwrite other important data and lead to unexpected behavior, including privilege escalation and, in worst cases, a system compromise.

Conceptual Example Code

Here’s a conceptual example of how this vulnerability might be exploited. This pseudocode simulates the scenario of an out-of-bounds write:

# Attacker already has System privileges
$ whoami
system
# Attempt to copy a crafted file using scp
$ scp crafted_file user@target:/path/to/destination
# The crafted_file triggers an out of bounds write in the scp process on the target system

In this example, `crafted_file` is a specially designed file that, when processed by scp, causes it to write data beyond its allocated memory space. Please note that this is a simplified representation of the exploit and the actual exploit would likely involve more sophisticated techniques.

Mitigation Guidance

To mitigate this vulnerability, users are advised to apply the vendor patch identified as ALPS09625562. In scenarios where applying the patch is not immediately feasible, the use of a Web Application Firewall (WAF) or Intrusion Detection System (IDS) is recommended as a temporary mitigation measure. However, these measures do not entirely eliminate the risk, but they can significantly reduce the likelihood of a successful exploit. Users are strongly encouraged to apply the patch as soon as possible to ensure maximum protection.