CVE-2026-52802

Gogs has an Open Redirect via redirect_to

Published

2026-06-23

Modified

2026-07-21

EPSS percentile

43%

Aliases

GHSA-xxhq-69mf-w8cr

Sources

github-advisory

Summary

### Summary An open redirect vulnerability exists in Gogs where attacker-controlled `redirect_to` parameters can bypass validation, allowing redirection to arbitrary external sites. ### Details All redirects in Gogs that are validated via the `IsSameSite` function are vulnerable: ```go func IsSameSite(url string) bool { return len(url) >= 2 && url[0] == '/' && url[1] != '/' && url[1] != '\\' } ``` The function only inspects the first two characters of the URL string. This check fails to account for directory traversal sequences followed by backslashes. For example: ``` /a/../\example.com ``` The `IsSameSite` function checks the input supplied to the `redirect_to` query parameter value `/a/../\example.com` and considers it valid. Because web browsers normalize backslashes `\` to forward slashes `/`, the normalized URL becomes `//example.com`. The normalized URL becomes: ``` //example.com ``` Resulting in a cross-origin redirect. This affects all endpoints using the `redirect_to` query parameter, including login and other post-action flows. ### PoC 1. An attacker can provide a user with a link to login to Gogs with a `redirect_to` query parameter that redirects a user to a site the attacker wants them to visit: ``` http://192.168.236.132:3000/user/login?redirect_to=/a/../\example.com ``` 2. After the user successfully logs in, they would be redirected to the site an attacker wants them to visit: ### Impact * Phishing: Attackers can use trusted domain links to redirect victims to credential-harvesting pages * OAuth/SSO Token Theft: In authentication flows, authorization codes or tokens may leak via redirect * Referer Leakage: Sensitive URL parameters may be exposed to attacker domains via the Referer header * Cache Poisoning: In deployments with shared caches, malicious redirects may be cached and served to other users

Affected packages

Remediation: Upgrade to 0.14.3 or later.

References

• https://github.com/advisories/GHSA-xxhq-69mf-w8cr