PT-2026-51621 · Go · Gogs.Io/Gogs

Published

2026-06-23

·

Updated

2026-06-23

·

CVE-2026-52802

CVSS v3.1

5.4

Medium

VectorAV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

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
image

  1. After the user successfully logs in, they would be redirected to the site an attacker wants them to visit:
image image

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

Fix

Open Redirect

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Weakness Enumeration

CWE-601

Related Identifiers

CVE-2026-52802
GHSA-XXHQ-69MF-W8CR

Affected Products

Gogs.Io/Gogs