Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2023-28771
Zyxel Multiple Firewalls
AV AC PR UI S C I A CVSS EPSS %ile KEV
N L N N U H H H 9.8 .9928 99.9 YES
AFFECTED
Product Versions Fixed
ZyWALL/USG series firmware 4.60 through 4.73 – —
VPN series firmware 4.60 through 5.35 – —
USG FLEX series firmware 4.60 through 5.35 – —
ATP series firmware 4.60 through 5.35 – —
TIMELINE
Mar 23 Reserved by Zyxel
Apr 25 Published (CNA: Zyxel)
May 31 Added to CISA KEV, remediation due 2023-06-21
Description
Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| March 23, 2023 | Reserved | Reserved by Zyxel |
| April 25, 2023 | Published | Published (CNA: Zyxel) |
| May 31, 2023 | KEV ADDED | Added to CISA KEV, remediation due 2023-06-21 |
Affected
Affected products and packages — 4 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| Zyxel | ZyWALL/USG series firmware | — | 4.60 through 4.73 | — |
| Zyxel | VPN series firmware | — | 4.60 through 5.35 | — |
| Zyxel | USG FLEX series firmware | — | 4.60 through 5.35 | — |
| Zyxel | ATP series firmware | — | 4.60 through 5.35 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2023-28771 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
