CVE-2021-27342

MEDIUM

D-Link Router DIR-842 v3.0.2 - Auth Bypass

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2021-27342. PoCs published by mavlevin.

AI-analyzed exploit summary This exploit bypasses authentication throttling in D-Link routers via a timing side-channel, allowing brute-force attacks on the telnet service with reduced delays. It leverages socket interactions to detect successful authentication by analyzing response timing.

Description

An authentication brute-force protection mechanism bypass in telnetd in D-Link Router model DIR-842 firmware version 3.0.2 allows a remote attacker to circumvent the anti-brute-force cool-down delay period via a timing-based side-channel attack

Exploits (2)

nomisec WORKING POC 14 stars
by mavlevin · poc
https://github.com/mavlevin/D-Link-CVE-2021-27342-exploit

This exploit bypasses authentication throttling in D-Link routers via a timing side-channel, allowing brute-force attacks on the telnet service with reduced delays. It leverages socket interactions to detect successful authentication by analyzing response timing.

Classification
Working Poc 95%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: D-Link routers (specific versions affected by CVE-2021-27342)
No auth needed
Prerequisites: Network access to the target device's telnet service (port 23) · A wordlist for brute-forcing passwords
devstral-2 · analyzed Feb 16, 2026 Full analysis →
inthewild WORKING POC
poc
https://github.com/guywhataguy/d-link-cve-2021-27342-exploit

This repository contains a functional exploit for CVE-2021-27342, which bypasses authentication throttling in D-Link routers' telnet service, allowing brute-force attacks with minimal delay between attempts.

Classification
Working Poc 95%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: D-Link routers (telnet service)
No auth needed
Prerequisites: network access to the target device · telnet service enabled on the target
devstral-2 · analyzed Feb 23, 2026 Full analysis →

Scores

CVSS v3 5.9
EPSS 0.0743
EPSS Percentile 92.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Details

CWE
CWE-203
Status published
Products (1)
dlink/dir-842e_firmware < 3.0.2
Published May 17, 2021
Tracked Since Feb 18, 2026