CVE-2021-23435
Open Redirect
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).
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Open Redirect
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).
- Record
CVE-2021-23435- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H - Updated
- 2026-11-02
EUVDEUVD-2021-1974
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).
- Record
EUVD-2021-1974- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-4hpq-rjcx-7vj9
Clearance Gem Open Redirect Vulnerability
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).
- Record
GHSA-4hpq-rjcx-7vj9- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H - Weakness
- CWE-601
- Updated
- 2026-11-02
NVD
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).
- Record
CVE-2021-23435- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H - CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 5.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
OSV
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).
- Record
CVE-2021-23435- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-4hpq-rjcx-7vj9
Clearance Gem Open Redirect Vulnerability
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).
- Record
GHSA-4hpq-rjcx-7vj9- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H - Weakness
- CWE-601
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
clearanceRubyGems |
before 2.5.0 | 2.5.0 |
clearanceRubyGems |
before 2.5.0, plus listed versions 0.10.00.10.10.10.20.10.3.20.10.4 Show 45 moreShow less0.10.50.11.00.11.10.11.20.12.00.13.00.13.20.14.00.15.00.16.00.16.10.16.20.16.30.8.20.8.30.8.40.8.50.8.60.8.70.8.80.9.0.rc10.9.0.rc20.9.0.rc30.9.0.rc40.9.0.rc50.9.0.rc60.9.0.rc70.9.0.rc80.9.0.rc90.9.11.0.01.0.0.rc11.0.0.rc21.0.0.rc31.0.0.rc41.0.0.rc61.0.0.rc71.0.0.rc81.0.11.1.01.10.11.11.01.12.01.12.11.13.0 |
2.5.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-23435 is a high vulnerability (CVSS 7.6) in Thoughtbot Clearance, published September 12, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.70%, the 53rd percentile. Fixed in clearance 2.5.0.
References
Left out here: 33 versions. The JSON record has them.