CVE-2019-15803
9.1 · CRITICALOverview
CVE-2019-15803 is a critical-severity vulnerability affecting zyxel gs1900-8_firmware. It was published on November 14, 2019 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an undocumented sequence of keypresses, undocumented functionality is triggered. A diagnostics shell is triggered via CTRL-ALT-t, which prompts for the password returned by fds_sys_passDebugPasswd_ret(). The firmware contains access control checks that determine if remote users are allowed to access this functionality. The function that performs this check (fds_sys_remoteDebugEnable_ret in libfds.so) always return TRUE with no actual checks performed. The diagnostics menu allows for reading/writing arbitrary registers and various other configuration parameters which are believed to be related to the network interface chips.
Remediation
Check the references section for vendor advisories and patches from zyxel. Update gs1900-8_firmware to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| zyxel | gs1900-8_firmware | >= 0, < 2.50\(aahh.0\)c0 | Affected |
| zyxel | gs1900-8hp_firmware | >= 0, < 2.50\(aahi.0\)c0 | Affected |
| zyxel | gs1900-10hp_firmware | >= 0, < 2.50\(aazi.0\)c0 | Affected |
| zyxel | gs1900-16_firmware | >= 0, < 2.50\(aahj.0\)c0 | Affected |
| zyxel | gs1900-24e_firmware | >= 0, < 2.50\(aahk.0\)c0 | Affected |
| zyxel | gs1900-24_firmware | >= 0, < 2.50\(aahl.0\)c0 | Affected |
| zyxel | gs1900-24hp_firmware | >= 0, < 2.50\(aahm.0\)c0 | Affected |
| zyxel | gs1900-48_firmware | >= 0, < 2.50\(aahn.0\)c0 | Affected |
| zyxel | gs1900-48hp_firmware | >= 0, < 2.50\(aaho.0\)c0 | Affected |
Frequently Asked Questions
What is CVE-2019-15803?
CVE-2019-15803 is a critical-severity vulnerability affecting zyxel gs1900-8_firmware. It was published on November 14, 2019 and has a CVSS 3.1 base score of 9.1 (CRITICAL).
How severe is CVE-2019-15803?
This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2019-15803?
Check the references section for vendor advisories and patches from zyxel. Update gs1900-8_firmware to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2019-15803?
CyberStrike's AI-powered security agents can automatically detect CVE-2019-15803 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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