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ExploitedIn CISA KEVFix available

CVE-2023-33010

Exploitation confirmed. First attested on 2023-06-05 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2023-05-24
  • Fixed in5.36
  • WeaknessCWE-120

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.

Timeline

dates in UTC
  1. 2023-05-2413:15CVE publishedNVD
  2. 2023-06-05Added to the CISA KEV catalogCISA KEV
  3. 2023-06-05Listed as exploited by GCVEGCVE
  4. 2023-06-05Exploitation first reportedCISA KEV
  5. 2025-01-1619:00SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-33010?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-33010?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Zyxel atp100 firmwareversion to verify
BranchAffectedFixed in
5.36≥ 4.32, < 5.365.36
5.36= 5.36no fix published
Zyxel atp100w firmwareversion to verify
BranchAffectedFixed in
5.36≥ 4.32, < 5.365.36
5.36= 5.36no fix published
Zyxel atp200 firmwareversion to verify
BranchAffectedFixed in
5.36≥ 4.32, < 5.365.36
5.36= 5.36no fix published

20 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA6 products

As Zyxel, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Zyxel ATP series firmware
    Affected
    • = 4.32 through 5.36 Patch 1no fix stated
  • Zyxel USG FLEX series firmware
    Affected
    • = 4.50 through 5.36 Patch 1no fix stated
  • Zyxel USG FLEX 50(W) firmware
    Affected
    • = 4.25 through 5.36 Patch 1no fix stated
  • Zyxel USG20(W)-VPN firmware
    Affected
    • = 4.25 through 5.36 Patch 1no fix stated
  • Zyxel VPN series firmware
    Affected
    • = 4.30 through 5.36 Patch 1no fix stated
  • Zyxel ZyWALL/USG series firmware
    Affected
    • = 4.25 through 4.73 Patch 1no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2023-05-24

Fix

  1. Update Zyxel atp100 firmware to 5.36
  2. CISA’s required action: Apply updates per vendor instructions.due 2023-06-26

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2023-06-05
Patch Due Date
2023-06-26
Ransomware Use
Unknown
Required Action
Apply updates per vendor instructions.

Sources

  • CISA KEVKEV entry2023-06-05
  • ENISA EUVDexploitation2023-06-052023-06-05
  • GCVEexploitation2023-06-05
  • CISA-ADPSSVC decisionactive2025-01-16
  • OpenCVESSVC decisionactive—
  • CNACVSS 3.19.8known since 2026-10-23
  • NVDCVSS 3.19.8read 2026-10-23
  • CNAweakness (CWE)CWE-120known since 2026-10-23
  • NVDweakness (CWE)CWE-120read 2026-10-23
  • FIRST EPSSEPSS score29.0 %read 2026-11-02
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2023-05-24
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-fqv9-84fh-jjgr

Frequently asked questions

What is CVE-2023-33010?

A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.

Is CVE-2023-33010 actively exploited?

Yes. CVE-2023-33010 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2023-06-26.

What is the CVSS score for CVE-2023-33010?

CVE-2023-33010 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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