CVE-2023-34139

highpriority · track · 35EPSS 0.008 · 55 %ileDEEURUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.76% (55th) EPSS

CVSS 8.8 · high

Is it mine?

19 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

EPSS · scored 2026-10-27

A command injection vulnerability in the Free Time WiFi hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.36 Patch 2 and VPN series firmware versions 4.20 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device.

cvss

Technical severity, 0–10. One row per scoring source.

8.8

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.18.8highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 5.9

v3.18.8highAV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.18.8highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU

v3.18.8highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · security@zyxel.com.twexploitability 2.8 · impact 5.9

v3.18.1highCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-78USprimaryCWE-78US

affected products (19)

Products and version ranges known to be affected.

Zyxel USG FLEX series firmware≤ 4.50 through 5.36 Patch 2enisa_euvdEU
Zyxel VPN series Firmware≤ 4.20 through 5.36 Patch 2enisa_euvdEU
Zyxel Communications Corp. USG FLEX4.50 → 5.36 Patch 2fstec_bduRU
Zyxel Communications Corp. VPN4.20 → 5.36 Patch 2fstec_bduRU
zyxel usg 2200-vpn firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:usg_2200-vpn_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 100 firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 100w firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 200 firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 50 firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 500 firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 50w firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:*
zyxel usg flex 700 firmware4.50 → 5.37nvdUScpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn 100 firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn_100_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn 300 firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn_300_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn 50 firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn_50_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn100 firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn100_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn2s firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn2s_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn300 firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn300_firmware:*:*:*:*:*:*:*:*
zyxel zywall vpn50 firmware4.20 → 5.37nvdUScpe:2.3:o:zyxel:zywall_vpn50_firmware:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2023-1765Zyxel Firewall: Mehrere SchwachstellenDeutsch2023-07-17csaf · cert_bundDE
Ein Angreifer aus dem angrenzenden Netz kann mehrere Schwachstellen in Zyxel Firewall ausnutzen, um beliebigen Programmcode auszuführen oder einen Denial of Service Zustand herbeizuführen.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd cert_bund NVD CVE.org MITRE

published 2023-07-17modified 2026-06-17

related (7,947)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2026-106931US	—OT critical	2.53% (85th)	KEV	2026-10-14
SiteGuard Server Edition contains an OS command injection vulnerability, which may allow an attacker to execute arbitrary OS commands with root or SYSTEM privileges on the system r…
CVE-2026-110447US	critical9.8OT critical	11.6% (96th)	KEV	2026-10-14
Collabora Online Built-in CODE Server before 26.4.303 (richdocumentscode), a Nextcloud app, allows remote code execution, as exploited in the wild in September and October 2026, a…
CVE-2026-105134US	critical10.0OT critical	81.8% (100th)	KEV	2026-10-04
A flaw has been found in Ahsay AhsayCBS up to 9.15.2.69/10.3.4.44. This vulnerability affects unknown code of the file /rps/api/json/UpdateReceivers.do of the component Replication…
CVE-2026-83549US	—OT critical	9.89% (96th)	KEV	2026-09-01
Post-authentication Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability has been identified in the SMA1000 Appliance Management…
CVE-2026-74233US	critical9.8OT critical	3.37% (89th)	—	2026-08-27
Zbtlink WE1326, WE357, WE5926, WE5926-WD, WE826-Q, WE826-T2, WE826-WD, WG108, and WG3526 firmware 19.1101, Zbtlink WE2426-C firmware 19.1112, Zbtlink WE5926-EC_QP firmware 20.0516,…

+7942 more

references (4)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan