Answer in brief
CVE-2023-28771 records a High severity vulnerability in CVE Program Container. The current sources mark it as known exploited. The current feed maps Zyxel/ATP series firmware (generic), Zyxel/USG FLEX series firmware (generic), Zyxel/VPN series firmware (generic), Zyxel/ZyWALL/USG series firmware (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Zyxel/ATP series firmware (generic), Zyxel/USG FLEX series firmware (generic), Zyxel/VPN series firmware (generic), Zyxel/ZyWALL/USG series firmware (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Zyxel/ATP series firmwaregeneric | 4.60 through 5.35 | Not reported |
| Zyxel/USG FLEX series firmwaregeneric | 4.60 through 5.35 | Not reported |
| Zyxel/VPN series firmwaregeneric | 4.60 through 5.35 | Not reported |
| Zyxel/ZyWALL/USG series firmwaregeneric | 4.60 through 4.73 | Not reported |
Published upstream
Apr 25, 2023
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
May 31, 2023
Evidence: source:kev:kev:kev:recordImproper 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.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2023-28771 records a High severity vulnerability in CVE Program Container. The current sources mark it as known exploited. The current feed maps Zyxel/ATP series firmware (generic), Zyxel/USG FLEX series firmware (generic), Zyxel/VPN series firmware (generic), Zyxel/ZyWALL/USG series firmware (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Zyxel/ATP series firmware (generic), Zyxel/USG FLEX series firmware (generic), Zyxel/VPN series firmware (generic), Zyxel/ZyWALL/USG series firmware (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Zyxel/ATP series firmwaregeneric | 4.60 through 5.35 | Not reported |
| Zyxel/USG FLEX series firmwaregeneric | 4.60 through 5.35 | Not reported |
| Zyxel/VPN series firmwaregeneric | 4.60 through 5.35 | Not reported |
| Zyxel/ZyWALL/USG series firmwaregeneric | 4.60 through 4.73 | Not reported |
Published upstream
Apr 25, 2023
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
May 31, 2023
Evidence: source:kev:kev:kev:recordImproper 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.
Quoted source text, attributed separately from HOL analysis.