Exploitation evidence
Known exploited · CISA KEV listed
Added 2023-06-05. Ransomware campaign use: Unknown.
CISA required action: Apply updates per vendor instructions.
CISA due date: 2023-06-26. This is the catalog’s deadline, not an assessment of your organization’s exposure.
KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗Reported products and versions
Zyxel / ATP series firmware
Default status: unaffected
- affected: 4.60 through 5.36 Patch 1
Zyxel / USG FLEX series firmware
Default status: unaffected
- affected: 4.60 through 5.36 Patch 1
Zyxel / USG FLEX 50(W) firmware
Default status: unaffected
- affected: 4.60 through 5.36 Patch 1
Zyxel / USG20(W)-VPN firmware
Default status: unaffected
- affected: 4.60 through 5.36 Patch 1
Zyxel / VPN series firmware
Default status: unaffected
- affected: 4.60 through 5.36 Patch 1
Zyxel / ZyWALL/USG series firmware
Default status: unaffected
- affected: 4.60 through 4.73 Patch 1
Fixes and workarounds
No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.
Sources and related reporting
Observed change timeline
History begins when Egret first downloads each source. It is not the complete upstream CVE history.
12 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-12",
"epss": 0.28144,
"percentile": 0.98138
}10 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.28144,
"percentile": 0.98126
}09 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-09",
"epss": 0.28144,
"percentile": 0.98124
}08 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-08",
"epss": 0.28144,
"percentile": 0.98123
}07 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-07",
"epss": 0.28144,
"percentile": 0.98122
}06 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-06",
"epss": 0.28144,
"percentile": 0.9812
}06 Nov 2026, 06:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-05",
"epss": 0.28144,
"percentile": 0.98118
}04 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-04",
"epss": 0.28144,
"percentile": 0.98118
}04 Nov 2026, 18:20 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
{
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"url": "https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls"
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"timestamp": "2025-02-04T16:14:56.233928Z",
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"metrics": [
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"orgId": "96e50032-ad0d-4058-a115-4d2c13821f9f",
"shortName": "Zyxel"
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"references": [
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}
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"cveId": "CVE-2023-33009",
"datePublished": "2023-05-24T00:00:00.000Z",
"dateReserved": "2023-05-17T00:00:00.000Z",
"dateUpdated": "2025-10-21T23:05:47.636Z",
"state": "PUBLISHED"
},
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}03 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-03",
"epss": 0.28144,
"percentile": 0.98114
}03 Nov 2026, 02:22 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-02",
"epss": 0.28144,
"percentile": 0.98111
}03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed
Stored KEV snapshot at this observation.
{
"cveID": "CVE-2023-33009",
"cwes": [
"CWE-120"
],
"dateAdded": "2023-06-05",
"dueDate": "2023-06-26",
"forensicTriage": "No",
"knownRansomwareCampaignUse": "Unknown",
"notes": "https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls; https://nvd.nist.gov/vuln/detail/CVE-2023-33009",
"product": "Multiple Firewalls",
"requiredAction": "Apply updates per vendor instructions.",
"shortDescription": "Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow vulnerability in the notification function that could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and remote code execution on an affected device.",
"vendorProject": "Zyxel",
"vulnerabilityName": "Zyxel Multiple Firewalls Buffer Overflow Vulnerability"
}