CVE-2022-40603

CVE-2022-40603 is a medium-severity vulnerability in Zyxel Atp800 Firmware with a CVSS 3.x base score of 4.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

• Severity: Medium (CVSS 3.x base score 4.7)
• EPSS exploit prediction: 0% (28th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-79
• Affected product: Zyxel Atp800 Firmware
• Published: 2022-12-06
• Last modified: 2026-06-17

Description

A cross-site scripting (XSS) vulnerability in the CGI program of Zyxel ZyWALL/USG series firmware versions 4.30 through 4.72, VPN series firmware versions 4.30 through 5.31, USG FLEX series firmware versions 4.50 through 5.31, and ATP series firmware versions 4.32 through 5.31, which could allow an attacker to trick a user into visiting a crafted URL with the XSS payload. Then, the attacker could gain access to some browser-based information if the malicious script is executed on the victim’s browser.

Frequently asked questions

What is CVE-2022-40603?

A cross-site scripting (XSS) vulnerability in the CGI program of Zyxel ZyWALL/USG series firmware versions 4.30 through 4.72, VPN series firmware versions 4.30 through 5.31, USG FLEX series firmware versions 4.50 through 5.31, and ATP series firmware versions 4.32 through 5.31, which could allow an attacker to trick a user into visiting a crafted URL with the XSS payload. Then, the attacker could gain access to some browser-based information if the malicious script is executed on the victim’s browser.

How severe is CVE-2022-40603?

CVE-2022-40603 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2022-40603 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2022-40603?

CVE-2022-40603 primarily affects Zyxel Atp800 Firmware. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2022-40603?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2022-40603 published?

CVE-2022-40603 was published on 2022-12-06 and last updated on 2026-06-17.

References

• https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-xss-vulnerability-in-firewalls

Affected products (19)

• cpe:2.3:o:zyxel:atp800_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:atp700_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:atp500_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:atp100w_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg40_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg40w_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg60_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:zyxel:usg60w_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Zyxel Atp800 Firmware

• CVE-2023-33010 — Critical (CVSS 9.8): A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36…
• CVE-2023-33009 — Critical (CVSS 9.8): A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36…
• CVE-2023-28771 — Critical (CVSS 9.8): Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware…
• CVE-2022-30525 — Critical (CVSS 9.8): A OS command injection vulnerability in the CGI program of Zyxel USG FLEX 100(W) firmware versions 5.00 through 5.21…
• CVE-2022-0342 — Critical (CVSS 9.8): An authentication bypass vulnerability in the CGI program of Zyxel USG/ZyWALL series firmware versions 4.20 through…
• CVE-2020-29583 — Critical (CVSS 9.8): Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The…

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