Summary
A CAPTCHA bypass vulnerability in the 1Panel authentication API allows an unauthenticated attacker to disable CAPTCHA verification by abusing a client-controlled parameter. Because the server previously trusted this value without proper validation, CAPTCHA protections could be bypassed, enabling automated login attempts and significantly increasing the risk of account takeover (ATO).
Details
The /api/login endpoint accepts a boolean field named ignoreCaptcha directly from the client request body:
"ignoreCaptcha": true
The backend implementation uses this value to determine whether CAPTCHA validation should be performed:
if !req.IgnoreCaptcha {
if errMsg := captcha.VerifyCode(req.CaptchaID, req.Captcha); errMsg != "" {
helper.BadAuth(c, errMsg, nil)
return
}
}
Because req.IgnoreCaptcha is taken directly from user input—with no server-side validation, no session binding, and no privilege checks—any unauthenticated attacker can force CAPTCHA validation to be skipped.
There are no additional conditions, such as:
no requirement for MFA
no trusted device
no IP reputation checks
no prior valid session
no rate limiting
This results in CAPTCHA being entirely client-controlled, which violates fundamental authentication and anti-automation security assumptions.
References
aliyevmursal Reporter
Summary
A CAPTCHA bypass vulnerability in the 1Panel authentication API allows an unauthenticated attacker to disable CAPTCHA verification by abusing a client-controlled parameter. Because the server previously trusted this value without proper validation, CAPTCHA protections could be bypassed, enabling automated login attempts and significantly increasing the risk of account takeover (ATO).
Details
The /api/login endpoint accepts a boolean field named ignoreCaptcha directly from the client request body:
"ignoreCaptcha": trueThe backend implementation uses this value to determine whether CAPTCHA validation should be performed:
Because req.IgnoreCaptcha is taken directly from user input—with no server-side validation, no session binding, and no privilege checks—any unauthenticated attacker can force CAPTCHA validation to be skipped.
There are no additional conditions, such as:
no requirement for MFA
no trusted device
no IP reputation checks
no prior valid session
no rate limiting
This results in CAPTCHA being entirely client-controlled, which violates fundamental authentication and anti-automation security assumptions.
References