critical Known exploitedREV. 01
CVE-2023-33009Zyxel firewalls — overflow in the notification function
A buffer overflow in the notification function of Zyxel's firewall firmware lets an attacker with no credentials crash the device or execute code on it. Firmware from 4.60 up to 5.36 Patch 1 is affected across the product line.
Read the risk
THE VITAL STATS- CVSS score
- 9.8/ 10 CVSS v3.1
- EPSS probability
- 28% Likelihood of exploitation
- Attack complexity
- Low Conditions needed to exploit
- Known exploited
- Yes — CISA KEV
- CVE published
- 2023-05-24
- Added to KEV
- 2023-06-05
- Exploit published
- Not recorded
- Confidence
- high
- Kill chain
- initial access
- MITRE ATT&CK
- T1190
- Severity
- critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attacker needsNetwork access to the affected service on the device.
Behind the card
3 REFERENCES- 01CVE recordNVD recordnvd.nist.gov
- 02CISACISA Known Exploited Vulnerabilities catalogcisa.gov
- 03Vendor advisoryzyxel.comzyxel.com
Field-level provenanceTRACE THE SOURCES +
Which source supports each field, when it was retrieved, and who extracted it.
| Fields | Source | Retrieved | Extractor | Confidence |
|---|---|---|---|---|
| cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_at | nvd.nist.gov | 2026-09-24 | scrty-crds-pipeline/0.1 | high |
| exploitation.known_exploited, exploitation.kev_added | cisa.gov | 2026-09-24 | scrty-crds-pipeline/0.1 | high |
| epss | api.first.org | 2026-09-24 | scrty-crds-pipeline/0.1 | high |
| title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisites | nvd.nist.gov | 2026-09-24 | claude-code | high |
Printing history
THE RECORD- r1Initial base card
First printing. This card has not been reprinted since publication.