Cisco NSO NETCONF DoS via Unvalidated Package Upload: CVE-2023-20040 January 2023

A vulnerability in the NETCONF service of Cisco Network Services Orchestrator (NSO) could allow an authenticated, remote attacker to cause a denial of service (DoS) on an affected system that is running as the root user. To exploit this vulnerability, the attacker must be a member of the admin group. This vulnerability exists because user-supplied input is not properly validated when NETCONF is used to upload packages to an affected device. An attacker could exploit this vulnerability by uploading a specially crafted package file. A successful exploit could allow the attacker to write crafted files to arbitrary locations on the filesystem or delete arbitrary files from the filesystem of an affected device, resulting in a DoS condition. Note: By default, during install, Cisco NSO will be set up to run as the root user unless the --run-as-user option is used.

Vulnerability Analysis

CVE-2023-20040 is exploitable with network access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and a high impact on availability.

Attack Vector:

NETWORK

Attack Complexity:

LOW

Privileges Required:

HIGH

User Interaction:

NONE

Scope:

UNCHANGED

Confidentiality Impact:

NONE

Integrity Impact:

LOW

Availability Impact:

HIGH

Weakness Type

Relative Path Traversal

The software uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory. This allows attackers to traverse the file system to access files or directories that are outside of the restricted directory.

Products Associated with CVE-2023-20040

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Affected Versions

Exploit Probability

EPSS

1.50%

Percentile

80.90%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.