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CVE-2021-40556

HIGH
8.8
CVSS Score
Published: October 6, 2022 at 12:00 AM UTC
Updated: June 17, 2026 at 04:07 AM UTC
2 products affected across 1 vendorRt AX56U FirmwareRt-Ax56U

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Severity
HIGH8.8
Exploit prediction
EPSS 2%

Description

A stack overflow vulnerability exists in the httpd service in ASUS RT-AX56U Router Version 3.0.0.4.386.44266. This vulnerability is caused by the strcat function called by "caupload" input handle function allowing the user to enter 0xFFFF bytes into the stack. This vulnerability allows an attacker to execute commands remotely. The vulnerability requires authentication.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Rt AX56U Firmware· ASUS
95%
3.0.0.4.386.44266
asus-rt-ax56u (same device)
Rt-Ax56U· ASUSdevice
80%
All versions

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

ProductVendor Advisory
Source: [email protected]
https://www.asus.com/tw/Networking-IoT-Servers/WiFi-Routers/ASUS-WiFi-Routers/RT-AX56U/HelpDesk_BIOS/
ExploitThird Party Advisory
Source: [email protected]
https://x1ng.top/2021/10/14/ASUS%E6%A0%88%E6%BA%A2%E5%87%BA%E6%BC%8F%E6%B4%9E%E5%88%86%E6%9E%90/

CVSS

8.8HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-787

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