CVE-2023-28771
Actively exploited. CVE-2023-28771 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-05-31) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.
Public exploit code is available. Proof-of-concept or working exploit code for CVE-2023-28771 is indexed in Metasploit and GitHub PoC. Expect opportunistic scanning and exploitation attempts — prioritize remediation.
Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG firewalls allow for improper error message handling which could allow an unauthenticated attacker to execute OS commands remotely by sending crafted packets to an affected device.
CSIRTS triage
- What
- Zyxel firewalls allow for improper error message handling leading to OS command injection.
- Who is affected
- Deployments of Zyxel ATP, USG FLEX, and other specified firewalls are affected.
- Urgency
- Immediate remediation is critical due to active exploitation and severity of the vulnerability.
- Action
- Update the firmware of affected Zyxel firewalls to mitigate the vulnerability.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 100% of all EPSS-scored CVEs.
Exploit availability
Public exploit or proof-of-concept code for CVE-2023-28771 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.
- MetasploitA Metasploit Framework module targets this CVE — weaponized, point-and-click exploitation.look it up ↗
- GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
Advisory coverage (1)
- criticalexploitedCVE-2023-28771: Zyxel Multiple Firewalls OS Command Injection Vulnerabilitycisa-kev · 2023-05-31
External references
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[](https://www.csirts.com/cve/CVE-2023-28771)