Full Report
[Control Systems] Moxa security advisory (AV26-938)
Analysis Summary
# Vulnerability: Moxa TN-4500B Series Out-of-Bounds Write
## CVE Details
- **CVE ID:** CVE-2026-15579
- **CVSS Score:** Not explicitly listed in the source, but typically rated **High** for Out-of-Bounds Write vulnerabilities in network infrastructure.
- **CWE:** CWE-787 (Out-of-bounds Write)
## Affected Systems
- **Products:** TN-4500B Series Ethernet Switches
- **Versions:** Firmware versions prior to or equal to v2.0
- **Configurations:** Systems running affected firmware versions in standard operational deployments.
## Vulnerability Description
An Out-of-bounds Write vulnerability exists in the TN-4500B Series Ethernet switches. This flaw occurs when the software writes data past the end of the intended buffer. In the context of an industrial Ethernet switch, this typically stems from improper validation of the length of incoming network packets or configuration data, potentially leading to memory corruption.
## Exploitation
- **Status:** Not specified as exploited in the wild; no public PoC currently referenced.
- **Complexity:** Low to Medium (Commonly associated with malformed packet injection).
- **Attack Vector:** Network (Remote exploitation is typical for this class of vulnerability in network switches).
## Impact
- **Confidentiality:** Moderate (Potential memory disclosure).
- **Integrity:** High (Potential for unauthorized modification of system state).
- **Availability:** High (Can lead to system crashes, Reboots, or Denial of Service (DoS) of critical industrial communication).
## Remediation
### Patches
- Moxa recommends updating the TN-4500B Series firmware to the latest available version. Users should consult the Moxa support portal for the specific firmware release addressing CVE-2026-15579.
### Workarounds
- Restrict management access to the switch to trusted IP addresses only.
- Disable unused services and protocols (e.g., Telnet, HTTP) if not required for operation.
- Implement network segmentation to isolate industrial control systems from external networks.
## Detection
- **Indicators of Compromise:** Unexpected system reboots, intermittent network connectivity loss, or unusual management traffic originating from unrecognized sources.
- **Detection methods and tools:** Use Industrial Control System (ICS) aware firewalls or Intrusion Detection Systems (IDS) to monitor for malformed traffic targeting management ports.
## References
- **Vendor Advisory:** hxxps[://]www[.]moxa[.]com/en/support/product-support/security-advisory/mpsa-252620-cve-2026-15579-out-of-bounds-write-vulnerability-in-ethernet-switch
- **Moxa Security Hub:** hxxps[://]www[.]moxa[.]com/en/rss/moxa-security-advisory
- **Cyber Centre Advisory:** hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/control-systems-moxa-security-advisory-av26-938