← gociux.comall exploited CVEs

Exploited vulnerability · CISA KEV

Is CVE-2023-28771 exploited? Yes: in CISA KEV since 31 May 2023

Gociux · Zyxel Multiple Firewalls · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2023-28771, Zyxel Multiple Firewalls OS Command Injection Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 31 May 2023, 36 days after it was published. It affects Zyxel Multiple Firewalls, an internet-facing product of the kind attackers use for initial access. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 31 May 2023
ransomwareNot knownno confirmed use
EPSStop 1%among the most likely CVEs to be exploited
severity9.8CVSS 3.1 · critical
US federal due21 Jun 2023BOD 22-01 deadline

What it is

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.

VendorZyxel (13 exploited CVEs in KEV)
ProductMultiple Firewalls
VulnerabilityZyxel Multiple Firewalls OS Command Injection Vulnerability
WeaknessCWE-78
Published25 Apr 2023
Added to KEV31 May 2023
Reported by (CNA)Zyxel

What to do

  1. Check whether you run it. Look for Multiple Firewalls in your asset inventory, including appliances and cloud images. Stack check lists every exploited Zyxel CVE at once.
  2. Apply the fix. Apply updates per vendor instructions.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 25 Apr 2023.
  4. Get told next time. Email alerts when CISA adds a CVE for Zyxel.

Other exploited CVEs in Multiple Firewalls

References

Questions

Is CVE-2023-28771 being exploited?

Yes. CISA added CVE-2023-28771 to the Known Exploited Vulnerabilities catalog on 31 May 2023, which means there is reliable evidence of exploitation in the wild.

Is CVE-2023-28771 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2023-28771?

Apply updates per vendor instructions. Check Zyxel's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Multiple Firewalls and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in May 2023 · Zyxel scorecard · act-now radar.

Running Zyxel in a regulated environment?

We check exposure across your estate, patch or mitigate with your team, and set up detection for what attackers do after exploiting it.

Get in touch →