CyberSecBulletin
CVE-2023-33237NVD status: Modified

TN-5900 Series: Improper Authentication

CVE-2023-33237 is a high-severity improper authentication vulnerability in TN-5900 Series from Moxa, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected TN-5900 Series versions: 1.0 through 3.3. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of TN-5900 Series you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on moxa.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
MoxaTN-5900 Series1.0 through 3.3Not stated
Moxatn-59001.0 through 3.3Not stated
MoxaTn-5900 Firmware3.3 and earlierNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA (moxa.com)
CVSS 3.18.8HighNVD

Official description

TN-5900 Series firmware version v3.3 and prior is vulnerable to improper-authentication vulnerability. This vulnerability arises from inadequate authentication measures implemented in the web API handler, allowing low-privileged APIs to execute restricted actions that only high-privileged APIs are allowed This presents a potential risk of unauthorized exploitation by malicious actors.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

How developers prevent this class of flaw

  • Use an authentication framework or library such as the OWASP ESAPI Authentication feature.

More Improper Authentication vulnerabilities (CWE-287)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in TN-5900 Series

All TN-5900 Series vulnerabilities

Recent Improper Authentication vulnerabilities

Spotted an error? Tell us.