Identify JWT vulnerabilities in security tests

Analyze, forge, and exploit JWT tokens in security testing

When you need to test JWT security (algorithm compliance, signature verification, expiration handling) in authorized penetration tests.

• · JWT token string
• · secret or algorithm weakness flag

• · decoded payload
• · vulnerability assessment (none, weak algo, no verification, expired)
• · forged token if exploitable

• · jwt.io CLI or library
• · hashcat (optional for brute-force)

• · JWT token is accessible
• · testing scope includes JWT endpoints

• · secret never guessed (strong key)
• · forged token rejected by strict validation
• · token refreshes prevent replay

• · Decodes all payload fields
• · Identifies weak algorithms (none, HS256 with weak secret)
• · Forging capability when secret is weak