CVE-2020-5233

MEDIUM5.9EPSS 0.29%

The pattern '/\domain.com' is not disallowed when redirecting, allowing for open redirect

發布日:2021/12/20修改日:2026/3/13

描述

### Impact An open redirect vulnerability has been found in `oauth2_proxy`. Anyone who uses `oauth2_proxy` may potentially be impacted. For a context [detectify] have an in depth blog post about the potential impact of an open redirect. Particularly see the OAuth section. **tl;dr**: People's authentication tokens could be silently harvested by an attacker. e.g: `facebook.com/oauth.php?clientid=123&state=abc&redirect_url=https://yourdomain.com/red.php?url%3dhttps://attacker.com/` ### Patches @sauyon found the issue, and has submitted a patch. ``` diff --git a/oauthproxy.go b/oauthproxy.go index 72ab580..f420df6 100644 --- a/oauthproxy.go +++ b/oauthproxy.go @@ -517,7 +517,7 @@ func (p *OAuthProxy) GetRedirect(req *http.Request) (redirect string, err error) // IsValidRedirect checks whether the redirect URL is whitelisted func (p *OAuthProxy) IsValidRedirect(redirect string) bool { switch { - case strings.HasPrefix(redirect, "/") && !strings.HasPrefix(redirect, "//"): + case strings.HasPrefix(redirect, "/") && !strings.HasPrefix(redirect, "//") && !strings.HasPrefix(redirect, "/\\"): return true case strings.HasPrefix(redirect, "http://") || strings.HasPrefix(redirect, "https://"): redirectURL, err := url.Parse(redirect) ``` This patch will be applied to the next release, which is scheduled for when this is publicly disclosed. ### Workarounds At this stage there is no work around.

受影響套件(2)

CVSS 分數

來源版本嚴重程度向量
osvCVSS 3.1MEDIUM5.9CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:H/A:L

參考連結(8)