Authentication Vulnerabilities

This page aggregates cross-platform resources to practice Authentication Vulnerabilities: retired Hack The Box machines, PortSwigger Web Security Academy labs and TryHackMe rooms, plus curated resources (HackTricks, PortSwigger, etc.) and related skills. Coverage: 33 challenges across 3 platforms — 4 HackTheBox · 27 PortSwigger · 2 TryHackMe. 4 with a Spanish writeup, 4 with a video writeup.

Where to start

Ordered by actual difficulty. At the same level: isolated lab first, then the guided room, and the full machine last.

PortSwigger — 2FA bypass using a brute-force attack (Apprentice) · 🇬🇧
PortSwigger — 2FA simple bypass (Apprentice) · 🇬🇧
PortSwigger — Authentication bypass via information disclosure (Apprentice) · 🇬🇧
PortSwigger — Authentication bypass via OAuth implicit flow (Apprentice) · 🇬🇧
PortSwigger — Broken brute-force protection, multiple credentials per request (Apprentice) · 🇬🇧
PortSwigger — Host header authentication bypass (Apprentice) · 🇬🇧

Curated resources

Source	Link
PortSwigger	https://portswigger.net/web-security/authentication

HTB machines practicing Authentication Vulnerabilities (4)

Machine	OS	Difficulty	Writeup
Cache	Linux	MEDIUM	🇪🇸 🇬🇧 📹
Epsilon	Linux	MEDIUM	🇪🇸 🇬🇧 📹
Helpline	Windows	HARD	🇪🇸 🇬🇧 📹
NodeBlog	Linux	EASY	🇪🇸 🇬🇧 📹

PortSwigger labs practicing Authentication Vulnerabilities (27)

Lab	Difficulty	Topic	Official
2FA bypass using a brute-force attack	APPRENTICE	Authentication Vulnerabilities	Open
2FA simple bypass	APPRENTICE	Authentication Vulnerabilities	Open
Authentication bypass via information disclosure	APPRENTICE	Information Disclosure	Open
Authentication bypass via OAuth implicit flow	APPRENTICE	OAuth Authentication	Open
Broken brute-force protection, multiple credentials per request	APPRENTICE	Authentication Vulnerabilities	Open
Host header authentication bypass	APPRENTICE	HTTP Host Header Attacks	Open
JWT authentication bypass via algorithm confusion	APPRENTICE	JWT (JSON Web Tokens)	Open
JWT authentication bypass via algorithm confusion with no exposed key	APPRENTICE	JWT (JSON Web Tokens)	Open
JWT authentication bypass via flawed signature verification	APPRENTICE	JWT (JSON Web Tokens)	Open
JWT authentication bypass via unverified signature	APPRENTICE	JWT (JSON Web Tokens)	Open
Password reset broken logic	APPRENTICE	Authentication Vulnerabilities	Open
Username enumeration via different responses	APPRENTICE	Authentication Vulnerabilities	Open
2FA broken logic	PRACTITIONER	Authentication Vulnerabilities	Open
Authentication bypass via encryption oracle	PRACTITIONER	Business Logic Vulnerabilities	Open
Authentication bypass via flawed state machine	PRACTITIONER	Business Logic Vulnerabilities	Open
Broken brute-force protection, IP block	PRACTITIONER	Authentication Vulnerabilities	Open
Brute-forcing a stay-logged-in cookie	PRACTITIONER	Authentication Vulnerabilities	Open
JWT authentication bypass via jku header injection	PRACTITIONER	JWT (JSON Web Tokens)	Open
JWT authentication bypass via jwk header injection	PRACTITIONER	JWT (JSON Web Tokens)	Open
JWT authentication bypass via kid header path traversal	PRACTITIONER	JWT (JSON Web Tokens)	Open
JWT authentication bypass via weak signing key	PRACTITIONER	JWT (JSON Web Tokens)	Open
Offline password cracking	PRACTITIONER	Authentication Vulnerabilities	Open
Password brute-force via password change	PRACTITIONER	Authentication Vulnerabilities	Open
Password reset poisoning via middleware	PRACTITIONER	Authentication Vulnerabilities	Open
Username enumeration via account lock	PRACTITIONER	Authentication Vulnerabilities	Open
Username enumeration via response timing	PRACTITIONER	Authentication Vulnerabilities	Open
Username enumeration via subtly different responses	PRACTITIONER	Authentication Vulnerabilities	Open

TryHackMe rooms practicing Authentication Vulnerabilities (2)

Room	Difficulty	Type	Access	Official
Advent of Cyber 3 (2021)	EASY	Walkthrough	🟢 Free	Open
Authentication Bypass	EASY	Walkthrough	🔵 VIP	Open

← Back to the full glossary Last updated: 2026-08-17

​Where to start

​Curated resources

​HTB machines practicing Authentication Vulnerabilities (4)

​PortSwigger labs practicing Authentication Vulnerabilities (27)

​TryHackMe rooms practicing Authentication Vulnerabilities (2)

Where to start

Curated resources

HTB machines practicing Authentication Vulnerabilities (4)

PortSwigger labs practicing Authentication Vulnerabilities (27)

TryHackMe rooms practicing Authentication Vulnerabilities (2)