1Panel – CAPTCHA Bypass via Client-Controlled Flag

### 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.

Source published

8 Dec 2025 17:56:27 UTC

Source modified

15 Dec 2025 19:56:03 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Publisher rating · HIGH