Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-3128

20
FAUCET Score

CVE-2021-3128 describes a routing loop vulnerability affecting several ASUS router models, including RT-AX3000, ZenWiFi AX (XT8), and RT-AX88U, running specific firmware versions. This flaw, triggered when IPv6 is active under particular network conditions, can lead to excessive network traffic between the router and the ISP, causing a denial of service. With a CVSS score of 7.5 (High), this vulnerability requires no user interaction or authentication, making it easily exploitable over the network. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.0.0.4.386.42095CPE matchmatch criteria
cpe:2.3:o:asus:zenwifi_ax_\(xt8\)_firmware:*:*:*:*:*:*:*:*
< 9.0.0.4.386.41994CPE matchmatch criteria
cpe:2.3:o:asus:zenwifi_ax_\(xt8\)_firmware:*:*:*:*:*:*:*:*
< 3.0.0.4.386.42095CPE matchmatch criteria
cpe:2.3:o:asus:rt-ax3000_firmware:*:*:*:*:*:*:*:*
< 9.0.0.4.386.41994CPE matchmatch criteria
cpe:2.3:o:asus:rt-ax3000_firmware:*:*:*:*:*:*:*:*
< 3.0.0.4.386.42095CPE matchmatch criteria
cpe:2.3:o:asus:rt-ax55_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.18%
Probability of exploitation in next 30 days
EPSS Percentile
80.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0218 is in the 65th percentile among its peer group of 51,485 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

asus.com / Networking-IoT-Servers/Whole-Home-Mesh-WiFi-System/ZenWiFi-WiFi-Systems/ASUS-ZenWiFi-AX-XT8-/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX3000/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX55/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX56U/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX58U/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX68U/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX82U/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX86U/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-6/All-series/RT-AX88U/HelpDesk_BIOS
ProductVendor Advisory
asus.com / Networking-IoT-Servers/WiFi-Routers/ASUS-WiFi-Routers/RT-AC66U-B1/HelpDesk_Download
ProductVendor Advisory
asus.com / supportonly/RT-AC1750_B1/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC1900/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC1900P/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC1900U/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC2900/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC3100/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC5300/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC58U/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC65U/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC68P/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC68R/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC68RW/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC68U/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC68W/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC85U/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC86U/HelpDesk_download
ProductVendor Advisory
asus.com / supportonly/RT-AC88U/HelpDesk_download
ProductVendor Advisory