GE UR family Improper Input Validation (CVE-2021-27420)

medium Tenable OT Security Plugin ID 503345

Synopsis

The remote OT asset is affected by a vulnerability.

Description

GE UR firmware versions prior to version 8.1x web server task does not properly handle receipt of unsupported HTTP verbs, resulting in the web server becoming temporarily unresponsive after receiving a series of unsupported HTTP requests. When unresponsive, the web server is inaccessible. By itself, this is not particularly significant as the relay remains effective in all other functionality and communication channels.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at CISA.gov.

GE strongly recommends users with impacted firmware versions update their UR devices to UR firmware Version 8.10, or greater to resolve these vulnerabilities. GE provides additional mitigations and information about these vulnerabilities in GE Publication Number: GES-2021-004 (login required).

GE recommends protecting UR IED by using network defense-in-depth practices. This includes, but is not limited to, placing UR IED inside the control system network security perimeter, and having access controls, monitoring (such as an Intrusion Detection System), and other mitigating technologies in place.

GE recommends users refer to the UR Deployment guide for secure configuration of UR IED and system.

Plugin Details

Severity: Medium

ID: 503345

Version: 1.2

Type: remote

Family: Tenable.ot

Published: 9/29/2025

Updated: 10/1/2025

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Low

Score: 1.4

CVSS v2

Risk Factor: Medium

Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS Score Source: CVE-2021-27420

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Vulnerability Information

CPE: cpe:/o:ge:multilin_l60_firmware, cpe:/o:ge:multilin_c30_firmware, cpe:/o:ge:multilin_l90_firmware, cpe:/o:ge:multilin_c70_firmware, cpe:/o:ge:multilin_l30_firmware, cpe:/o:ge:multilin_b90_firmware, cpe:/o:ge:multilin_f35_firmware, cpe:/o:ge:multilin_t35_firmware, cpe:/o:ge:multilin_t60_firmware, cpe:/o:ge:multilin_c95_firmware, cpe:/o:ge:multilin_c60_firmware, cpe:/o:ge:multilin_d60_firmware, cpe:/o:ge:multilin_g60_firmware, cpe:/o:ge:multilin_b30_firmware, cpe:/o:ge:multilin_m60_firmware, cpe:/o:ge:multilin_n60_firmware, cpe:/o:ge:multilin_g30_firmware, cpe:/o:ge:multilin_d30_firmware, cpe:/o:ge:multilin_f60_firmware

Required KB Items: Tenable.ot/GE

Exploit Ease: No known exploits are available

Patch Publication Date: 3/23/2022

Vulnerability Publication Date: 3/23/2022

Reference Information

CVE: CVE-2021-27420

CWE: 20

ICSA: 21-075-02

Detections

Analytics