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Vulnerability record · CVE-2019-15802 · published 14 November 2019

CVE-2019-15802: Zyxel gs1900-8 firmware hard-coded credentials vulnerability

Zyxel · Gs1900 8 Firmware

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. The firmware hashes and encrypts passwords using a hardcoded cryptographic key in sal_util_str_encrypt() in libsal.so.0.0. The parameters (salt, IV, and key data) are used to encrypt and decrypt all passwords using AES256 in CBC mode. With the parameters known, all previously encrypted passwords can be decrypted. This includes the passwords that are part of configuration backups or otherwise embedded as part of the firmware.

5.9 CVSS 3.1 Medium EPSS 1.5% · top 26.4% CWE-798 · Hard-coded credentials
5.9CVSS 3.1 base score, v2 4.3
1.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
9Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. The firmware hashes and encrypts passwords using a hardcoded cryptographic key in sal_util_str_encrypt() in libsal.so.0.0. The parameters (salt, IV, and key data) are used to encrypt and decrypt all passwords using AES256 in CBC mode. With the parameters known, all previously encrypted passwords can be decrypted. This includes the passwords that are part of configuration backups or otherwise embedded as part of the firmware.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

9 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html ExploitThird Party Advisory
https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml Vendor Advisory
https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html ExploitThird Party Advisory
https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2019-15802), CISA KEV, FIRST EPSS (scores of 2026-10-11). This page is refreshed as NVD updates the record.