CVE-2023-22915
CVE-2023-22915 is a high-severity vulnerability in Zyxel Usg Flex 100 Firmware with a CVSS 3.x base score of 7.5. 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-120.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 1% (60th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-120
- Affected product: Zyxel Usg Flex 100 Firmware
- Published:
- Last modified:
Description
A buffer overflow vulnerability in the “fbwifi_forward.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.30 through 5.35, USG20(W)-VPN firmware versions 4.30 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote unauthenticated attacker to cause DoS conditions by sending a crafted HTTP request if the Facebook WiFi function were enabled on an affected device.
Frequently asked questions
- What is CVE-2023-22915?
- A buffer overflow vulnerability in the “fbwifi_forward.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.30 through 5.35, USG20(W)-VPN firmware versions 4.30 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote unauthenticated attacker to cause DoS conditions by sending a crafted HTTP request if the Facebook WiFi function were enabled on an affected device.
- How severe is CVE-2023-22915?
- CVE-2023-22915 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2023-22915 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (60th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2023-22915?
- CVE-2023-22915 primarily affects Zyxel Usg Flex 100 Firmware. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2023-22915?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2023-22915 published?
- CVE-2023-22915 was published on 2023-04-24 and last updated on 2026-06-17.
References
Affected products (12)
- cpe:2.3:o:zyxel:usg_flex_100_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_50_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:*
- cpe:2.3:o:zyxel:usg_20w-vpn_firmware:*:*:*:*:*:*:*:*
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