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CVE-2026-41927NVD status: Deferred

WDR201A WiFi Extender: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-41927 is a high-severity stack-based buffer overflow vulnerability in WDR201A WiFi Extender from Shenzhen Yipu Commercial and Trading, with a CVSS 4.0 base score of 8.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected WDR201A WiFi Extender versions: 1.02.0 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.4% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of WDR201A WiFi Extender you run against the affected versions below, and install the vendor's latest release.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Shenzhen Yipu Commercial and TradingWDR201A WiFi Extender1.02.0 and earlierNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Attack requirements
NoneThe attack does not depend on a particular deployment or configuration.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Confidentiality (vulnerable system)
LowLimited loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
LowLimited loss of integrity on the vulnerable system.
Availability (vulnerable system)
HighSerious loss of availability on the vulnerable system.
Confidentiality (other systems)
NoneNo loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
NoneNo loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
NoneNo loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (vulncheck.com).

Official description

WDR201A WiFi Extender (HW V2.1, FW LFMZX28040922V1.02) contains a stack-based buffer overflow vulnerability in the firewall.cgi and makeRequest.cgi binaries that allows unauthenticated attackers to overwrite the saved return address by sending a POST request with a Content-Length header exceeding 512 bytes. Attackers can exploit insufficient length validation in the fgets() call to achieve arbitrary code execution through return-oriented programming or return-to-libc techniques.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

How developers prevent this class of flaw

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in WDR201A WiFi Extender

All WDR201A WiFi Extender vulnerabilities

Recent Stack-based Buffer Overflow vulnerabilities

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