CVE-2025-57821 Basecamp's Google Sign-In for Rails allowed redirects to a malformed URL
Attackers can redirect users to malicious sites via malformed URLs, potentially enabling session cookie injection attacks in Rails applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-57821?
CVE-2025-57821 is a medium-severity vulnerability in basecamp google_sign_in, published on 27 Aug 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Basecamp's Google Sign-In adds Google sign-in to Rails applications. Prior to version 1.3.0, it is possible to craft a malformed URL that passes the "same origin" check, resulting in the user being redirected to another origin. Rails applications configured to store the flash information in a session cookie may be vulnerable, if this can be chained with an attack that allows injection of arbitrary data into the session cookie. This issue has been patched in version 1.3.0. If upgrading is not possible at this time, a way to mitigate the chained attack can be done by explicitly setting SameSite=Lax or SameSite=Strict on the application session cookie.
Weakness: CWE-601
Which versions are affected by CVE-2025-57821?
2 open source packages ship an affected version, including google_sign_in.
| Package | Affected | Fixed in |
|---|---|---|
google_sign_in RubyGems | All versions | 1.3.0 |
google_sign_in RubyGems | All versions | 1.3.0 |
How do I fix CVE-2025-57821?
Upgrade google_sign_in to 1.3.0 or later.
Is CVE-2025-57821 being exploited?
There is no known exploitation of CVE-2025-57821 in the wild and no public exploit code.
Sources
Also known as GHSA-7pwc-wh6m-44q3.