CVE-2021-32030
Published: 06 May 2021
Summary
CVE-2021-32030 is a critical-severity Improper Authentication (CWE-287) vulnerability in Asus Lyra Mini Firmware. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 0.1% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 AC-17 (Remote Access) and AC-3 (Access Enforcement).
Deeper analysis
The vulnerability is an authentication bypass flaw (CWE-287) affecting the administrator web interface on ASUS GT-AC2900 routers running firmware prior to 3.0.0.4.386.42643 and Lyra Mini devices prior to 3.0.0.4_384_46630. It stems from improper handling in router/httpd/httpd.c (handle_request) and web_hook.o (auth_check), where an attacker-supplied null byte ('\0') can match the device's default credential value, granting unauthenticated access to administrative functions. All end-of-life Lyra Mini versions are also impacted.
An unauthenticated remote attacker can exploit the flaw over the network by sending a crafted request to the web interface, achieving full unauthorized access to the administrator application. With a CVSS score of 9.8, the issue requires no privileges or user interaction and can result in complete compromise of confidentiality, integrity, and availability of the device.
Advisories from ASUS and Atredis Partners recommend applying the fixed firmware versions listed on the vendor support pages for GT-AC2900 and Lyra Mini. Consumers can further mitigate exposure by disabling remote WAN access to the administrative interface, particularly on unsupported EOL devices where patches are unavailable.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-18896
Vulnerability details
The administrator application on ASUS GT-AC2900 devices before 3.0.0.4.386.42643 and Lyra Mini before 3.0.0.4_384_46630 allows authentication bypass when processing remote input from an unauthenticated user, leading to unauthorized access to the administrator interface. This relates to handle_request in router/httpd/httpd.c and…
more
auth_check in web_hook.o. An attacker-supplied value of '\0' matches the device's default value of '\0' in some situations. Note: All versions of Lyra Mini and earlier which are unsupported (End-of-Life, EOL) are also affected by this vulnerability, Consumers can mitigate this vulnerability by disabling the remote access features from WAN.
- CWE(s)
- KEV Date Added
- 02 June 2025
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly enforces authentication and access decisions on the httpd interface, blocking the null-byte bypass that grants unauthenticated admin access.
Restricts remote network access to the administrator application; disabling WAN exposure eliminates the attack vector described in the CVE.
Requires timely application of vendor firmware patches that correct the handle_request/auth_check flaw in supported devices.