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CVE-2019-15803

26
FAUCET Score

CVE-2019-15803 is a critical vulnerability affecting Zyxel GS1900 series devices with firmware versions prior to 2.50(AAHH.0)C0. It allows unauthenticated remote attackers to access an undocumented diagnostics shell by triggering a specific keypress sequence, bypassing access control checks that are erroneously configured to always return true for remote access. This flaw has a CVSS score of 9.1 (CRITICAL) due to its network-based attack vector, low complexity, and high impact on confidentiality and integrity, as it grants the ability to read/write arbitrary registers and configuration parameters. There is currently no public exploit code available, nor is there evidence of active exploitation or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 2.50\(aahh.0\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:gs1900-8_firmware:*:*:*:*:*:*:*:*
< 2.50\(aahi.0\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:gs1900-8hp_firmware:*:*:*:*:*:*:*:*
< 2.50\(aazi.0\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:gs1900-10hp_firmware:*:*:*:*:*:*:*:*
< 2.50\(aahj.0\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:gs1900-16_firmware:*:*:*:*:*:*:*:*
< 2.50\(aahk.0\)c0CPE matchmatch criteria
cpe:2.3:o:zyxel:gs1900-24e_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.1CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.32%
Probability of exploitation in next 30 days
EPSS Percentile
68.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0132 is in the 54th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

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