CVE-2021-23435 Open Redirect
Attackers can redirect users to external domains via manipulated session values in the Clearance Ruby gem, potentially facilitating phishing attacks.
- 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-2021-23435?
CVE-2021-23435 is a high-severity vulnerability in clearance, published on 12 Sep 2021. 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
This affects the package clearance before 2.5.0. The vulnerability can be possible when users are able to set the value of session[:return_to]. If the value used for return_to contains multiple leading slashes (/////example.com) the user ends up being redirected to the external domain that comes after the slashes (http://example.com).
Weakness: CWE-601
Which versions are affected by CVE-2021-23435?
2 open source packages ship an affected version, including clearance. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
clearance RubyGems | All versions | 2.5.0 |
clearance RubyGems | All versions | 2.5.0 |
Products include Thoughtbot Clearance.
How do I fix CVE-2021-23435?
Upgrade clearance to 2.5.0 or later.
Is CVE-2021-23435 being exploited?
There is no known exploitation of CVE-2021-23435 in the wild and no public exploit code.
Sources
Also known as GHSA-4hpq-rjcx-7vj9, SNYK-RUBY-CLEARANCE-1577284.