NVD / CVE Program· CNA Zyxel

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…

CriticalCVSS 9.8 · v3.1KEVWeaponized No fix recorded

Noroxi assessment

Priority: This week (action score 78/100)

CISA has confirmed exploitation in the wild (Jun 5, 2023). Remediation deadline for US federal agencies: Jun 26, 2023.
Probability of exploitation in the next 30 days: 29% (FIRST EPSS); higher than 98.1% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
According to the record, no fixed version is available yet.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Don’t wait for the next maintenance window. Until a fix is released, restrict access to the affected component and follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

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.

BDU:2023-02796

Published: May 24, 2023
Updated: Jun 17, 2026
EPSS: 29.0% · 98th percentile
CWE: CWE-120

Report tools

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Action score

This week

Don’t wait for the next maintenance window.

CVSS: 39 / 40 · 9.8 / 10
CISA KEV: 30 / 30 · Listed
EPSS: 9 / 30 · 29.0%

CISA SSVC decision

Exploitation: active
Automatable: yes
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 9.8
CNA · Zyxel: 9.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Jun 5, 2023. That signals real attacks, not theory.

Remediation deadline for US federal agencies: Jun 26, 2023.

Get told when this record changes

In CISA KEV: exploitation in the wild confirmed
Weaponized exploit exists
No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
zyxel	atp100 firmware	cpe:2.3:o:zyxel:atp100_firmware
zyxel	atp100	cpe:2.3:h:zyxel:atp100
zyxel	atp200 firmware	cpe:2.3:o:zyxel:atp200_firmware
zyxel	atp200	cpe:2.3:h:zyxel:atp200
zyxel	atp500 firmware	cpe:2.3:o:zyxel:atp500_firmware
zyxel	atp500	cpe:2.3:h:zyxel:atp500
zyxel	atp100w firmware	cpe:2.3:o:zyxel:atp100w_firmware
zyxel	atp100w	cpe:2.3:h:zyxel:atp100w
zyxel	atp700 firmware	cpe:2.3:o:zyxel:atp700_firmware
zyxel	atp700	cpe:2.3:h:zyxel:atp700
zyxel	atp800 firmware	cpe:2.3:o:zyxel:atp800_firmware
zyxel	atp800	cpe:2.3:h:zyxel:atp800

and 34 more

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Zyxel). Independent of NVD's CPE analysis and usually ahead of it.

Zyxel ATP series firmware
- 4.32 through 5.36 Patch 1affected
Zyxel USG FLEX 50(W) firmware
- 4.25 through 5.36 Patch 1affected
Zyxel USG FLEX series firmware
- 4.50 through 5.36 Patch 1affected
Zyxel USG20(W)-VPN firmware
- 4.25 through 5.36 Patch 1affected
Zyxel VPN series firmware
- 4.30 through 5.36 Patch 1affected
Zyxel ZyWALL/USG series firmware
- 4.25 through 4.73 Patch 1affected

Affected versions · NVD (20)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

zyxel atp100 firmware4.32 and later · before 5.36
zyxel atp100 firmware5.36
zyxel atp100w firmware4.32 and later · before 5.36
zyxel atp100w firmware5.36
zyxel atp200 firmware4.32 and later · before 5.36
zyxel atp200 firmware5.36
zyxel atp500 firmware4.32 and later · before 5.36
zyxel atp500 firmware5.36
zyxel atp700 firmware4.32 and later · before 5.36
zyxel atp700 firmware5.36
zyxel atp800 firmware4.32 and later · before 5.36
zyxel atp800 firmware5.36
zyxel usg 20w-vpn firmware5.36
zyxel usg 40 firmware4.25 and later · before 4.73
zyxel usg 40 firmware4.73
zyxel usg 40w firmware4.25 and later · before 4.73
zyxel usg 40w firmware4.73
zyxel usg 60 firmware4.25 and later · before 4.73
zyxel usg 60 firmware4.73
zyxel usg 60w firmware4.25 and later · before 4.73

Same product

zyxel: all records

Other highest-scoring records for the same primary product.

CVE-2023-28771Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.KEV
99Now
CVE-2023-33009A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX…KEV
77This week
CVE-2023-6764 A format string vulnerability in a function of the IPSec VPN feature in Zyxel ATP series firmware versions from 4.32 through…
32Monitor

Published before and after this one in the same product

← EarlierCVE-2022-38547Feb 6, 2023 · A post-authentication command injection vulnerability in the CLI command of Zyxel ZyWALL/USG series firmware versions 4.20 through 4.72…
29Monitor
Later →CVE-2023-6397Feb 19, 2024 · A null pointer dereference vulnerability in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1 and USG FLEX…
21Monitor
Later →CVE-2023-6398Feb 19, 2024 · A post-authentication command injection vulnerability in the file upload binary in Zyxel ATP series firmware versions from 4.32 through…
28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

PublishedMay 24, 2023
CISA KEVJun 5, 2023+12 d
TodayNov 14, 2026+1270 d

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-23-0291 · May 25, 2023(Zyxel Güvenlik Bildirimi)

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

The bug in code

The whole CWE-120 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

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Change log (0)

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls

Show all references (1 more)

www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-33010

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records