CVE-2023-28771Improper 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, an…
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It affects Zyxel ZyWALL/USG series firmware and 22 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since May 31, 2023; federal agencies had to remediate by Jun 21, 2023. Treat that date as your deadline.
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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.
- CVSS
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-78
- Known exploited
- Added to CISA KEV May 31, 2023; federal remediation due Jun 21, 2023Apply updates per vendor instructions.
- EPSS (exploitation in the next 30 days)
- 99.28% (percentile 100)
- Assigned by
- Zyxel
- NVD analysis
- Analyzed
- Record last updated
- Oct 21, 2025
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Zyxel ZyWALL/USG series firmware zyxel:zywall_usg_series_firmware (from the name) | 4.60 through 4.73 | CNA record |
Zyxel VPN series firmware zyxel:vpn_series_firmware (from the name) | 4.60 through 5.35 | CNA record |
Zyxel USG FLEX series firmware zyxel:usg_flex_series_firmware (from the name) | 4.60 through 5.35 | CNA record |
Zyxel ATP series firmware zyxel:atp_series_firmware (from the name) | 4.60 through 5.35 | CNA record |
zyxel atp100_firmware zyxel:atp100_firmware | from 4.60 before 5.36 | NVD |
zyxel atp100w_firmware zyxel:atp100w_firmware | from 4.60 before 5.35 | NVD |
zyxel atp200_firmware zyxel:atp200_firmware | from 4.60 before 5.36 | NVD |
zyxel atp500_firmware zyxel:atp500_firmware | from 4.60 before 5.36 | NVD |
zyxel atp700_firmware zyxel:atp700_firmware | from 4.60 before 5.36 | NVD |
zyxel atp800_firmware zyxel:atp800_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_100_firmware zyxel:usg_flex_100_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_100w_firmware zyxel:usg_flex_100w_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_200_firmware zyxel:usg_flex_200_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_50_firmware zyxel:usg_flex_50_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_500_firmware zyxel:usg_flex_500_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_50w_firmware zyxel:usg_flex_50w_firmware | from 4.60 before 5.36 | NVD |
zyxel usg_flex_700_firmware zyxel:usg_flex_700_firmware | from 4.60 before 5.36 | NVD |
zyxel vpn100_firmware zyxel:vpn100_firmware | from 4.60 before 5.36 | NVD |
zyxel vpn1000_firmware zyxel:vpn1000_firmware | from 4.60 before 5.36 | NVD |
zyxel vpn300_firmware zyxel:vpn300_firmware | from 4.60 before 5.36 | NVD |
zyxel vpn50_firmware zyxel:vpn50_firmware | from 4.60 before 5.36 | NVD |
zyxel zywall_usg_310_firmware zyxel:zywall_usg_310_firmware | from 4.60 before 4.73; 4.73 | NVD |
zyxel zywall_usg_100_firmware zyxel:zywall_usg_100_firmware | from 4.60 before 4.73; 4.73 | NVD |
References
- https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewallsvendor-advisory
- http://packetstormsecurity.com/files/172820/Zyxel-IKE-Packet-Decoder-Unauthenticated-Remote-Code-Execution.htmlexploit, third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-28771us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.