CVE-2023-28771
Zyxel — Zyxel Multiple Firewalls OS Command Injection Vulnerability
Zyxel · CWE-78 — Operating system command injection · in CISA KEV since 2023-05-31
EVRS 87 of 100 Immediate
Out-of-Band / Urgent Remediation
Rank 256 of 2,960 tracked
Why it scores 87
Evidence available: 6 of 7 signalsListed in the CISA KEV catalog, and an EPSS probability of 0.993.
- CISA KEVApplied
- RansomwareDid not apply
- Vendor exploitationDid not apply
- EPSSApplied
- Microsoft Exploitability IndexNot applicable
- Pre-patch disclosureNo data
- KEV recencyDid not apply
- CVSSApplied
The band answers “how soon”, not “how bad”. No data for: Pre-patch disclosure. Why some signals show no data
Fix
Patch or fixed version identifiedCISA required action
- www.zyxel.com/…/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls
- nvd.nist.gov/…/CVE-2023-28771
Fixed in
atp100 firmware: update to 5.36 or later | atp100w firmware: update to 5.35 or later | atp200 firmware: update to 5.36 or later | atp500 firmware: update to 5.36 or later | atp700 firmware: update to 5.36 or later | atp800 firmware: update to 5.36 or later
Affected versions
- atp100 firmware
>= 4.60 < 5.36 - atp100w firmware
>= 4.60 < 5.35 - atp200 firmware
>= 4.60 < 5.36 - atp500 firmware
>= 4.60 < 5.36 - atp700 firmware
>= 4.60 < 5.36 - atp800 firmware
>= 4.60 < 5.36 - usg flex 100 firmware
>= 4.60 < 5.36 - usg flex 100w firmware
>= 4.60 < 5.36
+30 more affected products; see the full list at NVD.
Remediation
Apply updates per vendor instructions.
Fixed versions from NVD.
Evidence
Each value with its source| Measure | Value | Source |
|---|---|---|
| CVSS base scoreHow severe the flaw is in itself. It does not say how likely an attack is. | 9.8 | NVD |
| FIRST EPSSFIRST's estimate of the chance this is exploited in the next 30 days, and how that ranks against all CVEs. | 0.993 (99.94th pctl) | FIRST EPSS |
| Actively exploitedWhether a source of record has confirmed attacks using it in the wild. | Confirmed | CISA KEV |
| Ransomware campaign useWhether CISA has seen ransomware operators use it. | Unknown or none | CISA KEV |
| CISA remediation deadlineThe date US federal agencies must have fixed or mitigated it. | 2023-06-21 · KEV since 2023 · listed over a year | CISA KEV |
| Public exploit moduleA module existing is not the same as active exploitation. | Public module exists | Metasploit |
| EUVD cross-referenceENISA's record: CVSS 9.8 (v3.1), assigned by Zyxel. | Listed | ENISA EUVD |
Description
NVDImproper 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.
What CISA says to do
- www.zyxel.com/…/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls
- nvd.nist.gov/…/CVE-2023-28771
Public module
Metasploit lists a public great-rank module for this CVE: Zyxel IKE Packet Decoder Unauthenticated Remote Code Execution (linux/misc/zyxel_ike_decoder_rce_cve_2023_28771). A module existing is not the same as active exploitation; see metasploit.com.