CVE-2023-28771
Confirmed PUBLISHEDImproper 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...
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
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.
- CVE Published
- Apr 25, 2023
- Exploitation Reported
- May 31, 2023
- CVSS
- 9.8 Critical
- EPSS
- 99.3%
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| Zyxel |
ZyWALL/USG series firmware
|
4.60 through 4.73 |
Affected |
| Zyxel |
VPN series firmware
|
4.60 through 5.35 |
Affected |
| Zyxel |
USG FLEX series firmware
|
4.60 through 5.35 |
Affected |
| Zyxel |
ATP series firmware
|
4.60 through 5.35 |
Affected |
CVE References
- zyxel.com/global/en/support/security-advisories/zyxel-... zyxel.com · CVE Record https://www.zyxel.com/global/en/support/security-advisories/zyxel-sec...
- packetstormsecurity.com/files/172820/Zyxel-IKE-Packet-Decoder-Unauth... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/172820/Zyxel-IKE-Packet-Decoder-...
Recommended Actions
- Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
- Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
- Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.
Known Exploited Vulnerability Sources
Catalogues that list this CVE as a known exploited vulnerability.
Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2023-05-31 00:00 UTC |
| The Shadowserver | 2026-05-27 00:00 UTC |
| Daily CyberSecurity | 2026-06-18 01:20 UTC |
Scanner Artifacts
Nuclei and Metasploit references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Metasploit | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/misc/zyxel_ike_decoder_rce_cve_2023_28771.rb | Apr 28, 2025 |
Virtual Patch
Compensating WAF rules to help reduce exposure to this CVE. Rule content and deployable vendor exports are available with KEVIntel Enterprise.
KEVIntel does not currently have a virtual patch for this CVE. When available, KEVIntel virtual patches ship as deployable ModSecurity, Cloudflare, and AWS WAF rules.
Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to KEVIntel Enterprise users.
CVSS Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitation Status
Exploited in the wild
Recorded 2023-05-31 00:00:00 UTC · CISA
Proof of concept available
Recorded 2023-05-23 02:37:39 UTC · GitHub
Weaknesses (CWE)
-
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Metasploit | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/misc/zyxel_ike_decoder_rce_cve_2023_28771.rb | Apr 28, 2025 |
Recent Mentions
Daily CyberSecurity · Jun 18, 2026
Zyxel has rolled out firmware patches for a serious flaw in its popular GS1900 series switches. Tracked as The post Zyxel Patches Stack-Based Buffer Overflow in GS1900 Switches (CVE-2026-7273) appeared first on Daily CyberSecurity. Related posts: Zyxel Firewalls Under Attack via Critical CVE-2023-28771 Total Takeover: Critical Zyxel Flaw (CVSS 9.8) Exposes Routers to Remote Command Injection Exploited in the Wild: Critical 9.8 CVSS RCE Hits Canon GUARDIANWALL MailSuite
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
github · Created 2023-05-23 02:37:39 UTC · 28 stars
PoC for CVE-2023-28771 based on Rapid7's excellent writeup
metasploit · Created Unknown
Metasploit module for CVE-2023-28771
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
01:20 UTC about 1 month ago01:20 UTC · about 1 month ago
KEV confirmed by Daily CyberSecurity
Exploitation attested by an external source
-
00:00 UTC about 2 months ago00:00 UTC · about 2 months ago
KEV confirmed by The Shadowserver
Exploitation attested by an external source
-
15:02 UTC about 1 year ago15:02 UTC · about 1 year ago
Metasploit module available
Exploit module available
-
00:00 UTC about 3 years ago00:00 UTC · about 3 years ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
02:37 UTC about 3 years ago02:37 UTC · about 3 years ago
Public PoC available
Public proof-of-concept code published
-
00:00 UTC about 3 years ago00:00 UTC · about 3 years ago
CVE published
Vulnerability disclosed publicly
-
00:00 UTC over 3 years ago00:00 UTC · over 3 years ago
CVE ID reserved
Identifier reserved by the CNA
Automate This Intelligence with the Pro API
Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
Pro API Example
GET /api/v2/pro/kevs/CVE-2023-28771
{
"cve_id": "CVE-2023-28771",
"title": "Improper error message handling in Zyxel ZyWALL/USG series firmware versions ...",
"affected_vendor": "Zyxel",
"affected_product": "ZyWALL/USG series firmware, VPN series firmware, USG FLEX series firmware, ATP series firmware",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 9.8,
"epss_score": 0.99284,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}