CyberSecBulletin
CVE-2025-2026NVD status: Deferred

NPort 6100-G2/6200-G2 Series: Improper Null Termination

Published Updated By the CyberSecBulletin desk

CVE-2025-2026 is a high-severity improper null termination vulnerability in NPort 6100-G2/6200-G2 Series from Moxa, with a CVSS 4.0 base score of 7.1 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 NPort 6100-G2/6200-G2 Series versions: 1.0.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of NPort 6100-G2/6200-G2 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
MoxaNPort 6100-G2/6200-G2 Series1.0.0Not 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.
Attack requirements
NoneThe attack does not depend on a particular deployment or configuration.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Confidentiality (vulnerable system)
NoneNo loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
NoneNo loss of integrity on the vulnerable system.
Availability (vulnerable system)
HighSerious loss of availability on the vulnerable system.
Confidentiality (other systems)
NoneNo loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
NoneNo loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
NoneNo loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (moxa.com).

Official description

The NPort 6100-G2/6200-G2 Series is affected by a high-severity vulnerability (CVE-2025-2026) that allows remote attackers to execute a null byte injection through the device’s web API. This may lead to an unexpected device reboot and result in a denial-of-service (DoS) condition. An authenticated remote attacker with web read-only privileges can exploit the vulnerable API to inject malicious input. Successful exploitation may cause the device to reboot, disrupting normal operations and causing a temporary denial of service.

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

The underlying weakness: Improper Null Termination

The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.

How developers prevent this class of flaw

  • Use a language that is not susceptible to these issues. However, be careful of null byte interaction errors (CWE-626) with lower-level constructs that may be written in a language that is susceptible.
  • Ensure that all string functions used are understood fully as to how they append null characters. Also, be wary of off-by-one errors when appending nulls to the end of strings.
  • If performance constraints permit, special code can be added that validates null-termination of string buffers, this is a rather naive and error-prone solution.

More Improper Null Termination vulnerabilities (CWE-170)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in NPort 6100-G2/6200-G2 Series

All NPort 6100-G2/6200-G2 Series vulnerabilities

Recent Improper Null Termination vulnerabilities

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